Glossary

A

Accountability (transparency): Accountability means it is clear which person or organisation is responsible for a piece of content and a website. It is a core trust signal.
AI Answer Box: An AI answer box is the summarized, directly formulated answer from an AI system that a user sees instead of a classic results list. Brands, products and source links may appear in it or be absent.
AI Crawler: AI crawlers are automated bots that fetch web pages for AI providers in order to find content, make it available for search functions, retrieve it for answers, or, depending on the provider, use it for model training.
AI Overviews: AI Overviews are AI-generated answer boxes from Google that appear above the classic search results. They summarize information from the web and can change click distribution.
AI Readiness Score: The AI Readiness Score is a maturity level that shows how well a website is prepared for AI search technically, structurally, in terms of content and trust. It is a scoring model, not an official industry standard.
AI Reputation: AI Reputation describes how a brand is perceived in AI answers, that is how often, how prominently, in what tone and based on which sources it appears. It results from the brand's own website, third-party sources and model behavior.
AI Visibility: AI Visibility describes whether and how visible a brand, website or person is in AI-generated answers. It measures mention, position, description and source linking across multiple platforms and prompts.
Alt Text: Alt text is a text alternative for an image, stored in the alt attribute of the img element, describing the content or function of the image.
Anchor Text: Anchor text is the clickable, visible text of a link. It gives users and search engines clues about what the linked target page is about.
Answer Engine Optimization (AEO) AEO: Answer Engine Optimization (AEO) optimizes content for direct answers such as featured snippets, FAQ answers or voice assistants. It focuses on answering frequently asked questions clearly and in an extractable way.
Application Programming Interface (API) API: An application programming interface (API) is an interface through which software systems communicate and exchange data. It defines how requests are made and answered.
ARIA ARIA: ARIA (Accessible Rich Internet Applications) is a standard that provides roles and attributes to make web content more accessible to assistive technologies when native HTML alone is not enough.
Article/BlogPosting Schema: Article and BlogPosting schema label editorial content such as blog posts or news in a structured way, providing context like title, author, date and image.
Author markup: Author markup is structured data that identifies authors or responsible organisations in a machine-readable way, typically via the author field in Article or BlogPosting schema.
Authority signals: Authority signals are indicators of the reputation and recognised competence of a person or organisation. They correspond to the A (Authoritativeness) in E-E-A-T.

B

Brand identity: Brand identity refers to the consistent description of a brand across its website, structured data and external profiles. It helps machines recognise the brand clearly and distinguish it from others.
Breadcrumb Navigation: Breadcrumb navigation shows a page's path within the website hierarchy. It improves user orientation and complements internal linking.
BreadcrumbList: BreadcrumbList is a schema type that describes a page's breadcrumb navigation in a structured way, making its position within the site hierarchy machine-readable.
Browser Caching: Caching stores previously retrieved content so it is available faster on repeat requests, relieving both servers and the network.

C

Call-to-Action (CTA) CTA: A call-to-action (CTA) is a targeted prompt designed to move users towards a specific action. Examples are buttons or links such as "Start free trial" or "Get in touch".
Canonical Tag: The canonical tag is an HTML link element that tells search engines the preferred (canonical) URL of a page. It helps consolidate duplicate or similar URLs onto a main version.
Canonicalization Signals: Canonicalization signals are all the cues search engines use to determine a page's canonical main version, including the canonical tag, internal links, the sitemap, redirects and hreflang.
Cascading Style Sheets (CSS) CSS: Cascading Style Sheets (CSS) is the language used to define the layout and design of web pages. CSS controls colours, fonts, spacing and arrangement, among other things.
ChatGPT-User: ChatGPT-User is the user agent documented by OpenAI for user-triggered retrieval. It fetches a page when a user enters a specific URL or query in ChatGPT.
Citability: Citability describes how well individual sections of a piece of content can be extracted, summarized and used as an answer by search engines and AI systems.
Citation Rate: Citation Rate measures the share of relevant AI answers in which a website is linked or named as a source. It is a monitoring metric, not an official ranking factor.
ClaudeBot: ClaudeBot is the web crawler used by Anthropic. Website owners can control its access via robots.txt and block it if needed.
Click-Through Rate (CTR) CTR: The click-through rate (CTR) indicates how many users click a search result relative to the number of times it is shown (impressions). It reflects how appealing a listing appears in search.
Client-Side Rendering (CSR) CSR: With Client-Side Rendering (CSR), the server delivers only a nearly empty HTML shell. The actual content is generated in the browser by JavaScript.
Content Decay: Content decay (stale content) refers to content that is outdated factually, chronologically or strategically and no longer reliably satisfies the current search intent.
Content Delivery Network (CDN) CDN: A content delivery network (CDN) is a network of distributed servers that delivers static content closer to the user, reducing loading times.
Content Management System (CMS) CMS: A content management system (CMS) is software for creating, managing and publishing web content, usually without programming knowledge. Well-known examples are WordPress or Shopify.
Core Update: A core update is a larger change to Google's ranking systems that re-evaluates the relevance and quality of content. It is not a penalty but a reassessment.
Core Web Vitals CWV: Core Web Vitals are a set of Google metrics that measure real-world user experience in the areas of loading performance, interactivity and visual stability.
Crawl Budget: Crawl budget describes how many URLs a search engine crawls on a site within a given period. It mainly becomes relevant for very large websites.
Crawl Depth: Crawl depth (also click depth) indicates how many clicks from the homepage are needed to reach a page. Important pages should be reachable as shallowly as possible.
Crawling: Crawling is the process by which a search engine bot fetches a URL and downloads its content. It is the first step before a page can be indexed.
Cumulative Layout Shift (CLS) CLS: Cumulative Layout Shift (CLS) measures how much visible elements shift unexpectedly during loading and represents the visual stability of a page.

D

Dead Links: Dead links are links pointing to a URL that is no longer reachable, usually returning status code 404. Internal dead links that lead users and crawlers into a dead end are especially problematic.
Document Object Model (DOM) DOM: The Document Object Model (DOM) is the structured representation of a web page that a browser uses to hold its content and structure in memory. JavaScript can modify the DOM to add or remove content.
Duplicate Content: Duplicate content refers to identical or very similar content reachable under several URLs. It rarely triggers a penalty but causes a loss of control over which version becomes the main one.

E

E-E-A-T E-E-A-T: E-E-A-T stands for Experience, Expertise, Authoritativeness and Trustworthiness. It is a quality framework from Google's Search Quality Rater Guidelines, not a single technical ranking factor.
Entity: An entity is a uniquely identifiable thing or concept, such as an organisation, person, brand, product, place or technical term. Search engines and AI systems process information as entities and their relationships.
Entity SEO: Entity SEO ensures that search engines and AI systems can clearly recognise brands, people, products, services and topics and relate them to one another. It goes beyond pure keyword optimisation.
Expertise: Expertise is the subject-matter competence behind a piece of content. It is the second E in E-E-A-T and should be visible through author details and supporting evidence.
Extensible Markup Language (XML) XML: Extensible Markup Language (XML) is a flexible text format for storing and exchanging data in a structured way. In the SEO context, the XML sitemap is best known.

F

Fact Density: Fact density describes how many concrete, verifiable pieces of information a text contains relative to general statements. It is an editorial quality criterion, not an official Google metric.
FAQPage Schema: FAQPage schema labels visible questions and answers on a page in a structured way. It may only be used when the FAQ content is actually visible on the page.
Featured Snippet: A featured snippet is a highlighted answer excerpt that Google displays above the classic results. It answers a query directly and is often called position zero.
Field Data (Real User Monitoring) RUM: Field data are performance measurements based on real users and their actual devices and connections. They show whether a performance problem is genuinely relevant.
Freshness: Freshness describes how current a piece of content is relative to the search intent. It is not equally important for every query.

G

Generative Engine Optimization (GEO) GEO: Generative Engine Optimization (GEO) covers measures that improve the chances of a brand or website being found, understood, extracted, classified and used as a source by generative AI answer systems. GEO extends classic SEO rather than replacing it.
Google Search Console (GSC) GSC: Google Search Console (GSC) is a free Google tool that shows how a website performs in organic search, with data on impressions, clicks, click-through rate and average position, plus indexing and technical issues.
Google-Extended: Google-Extended is a product token that lets you control certain AI uses by Google in robots.txt. It is not a separate HTTP user agent and is not the same as Googlebot.
Googlebot: Googlebot is Google's web crawler, which fetches web pages to crawl and index them for Google Search.
GPTBot: GPTBot is the crawler documented by OpenAI that typically fetches content for training future models. It can be specifically allowed or blocked via robots.txt.

H

H1 Heading: The H1 is a web page's main heading. It names the central topic, is visible to users and should generally appear only once per page.
Heading Hierarchy: The heading hierarchy is the logical nesting of headings from H1 to H6 that structures a page's content, much like a table of contents.
Helpful Content: Helpful content refers to content created primarily for people that delivers a clear answer and shows substance, originality and trust, rather than being optimized mainly for search engines.
High-Quality Content: High-quality content comes from better information value, not from more words. It fully answers the search intent, provides concrete facts, shows expertise and supports key statements with sources.
hreflang: hreflang is an HTML attribute that tells search engines the language and region of a page. It links language or regional variants of the same content to one another.
HTTP / HTTPS HTTP / HTTPS: HTTP (Hypertext Transfer Protocol) is the protocol through which browsers and servers exchange web content. HTTPS is the encrypted, secure variant of this protocol.
HTTP Status 200: HTTP status 200 (OK) means a page was found and served successfully. Only 200 URLs should appear in the sitemap and serve as canonical targets.
HTTP Status 301: HTTP status 301 signals a permanent redirect: a URL has been permanently replaced by another. Search engines transfer the signals to the target URL.
HTTP Status 302: HTTP status 302 signals a temporary redirect: content is temporarily available at a different URL. The original URL is meant to remain.
HTTP Status 404: HTTP status 404 (Not Found) means the server is reachable but the requested URL does not exist. Individual 404 errors are normal; internal dead links are the real problem.
Hydration: Hydration is the process of making server-delivered HTML interactive in the browser via JavaScript. The markup already exists; JavaScript only adds the behaviour.
HyperText Markup Language (HTML) HTML: HyperText Markup Language (HTML) is the markup language for web pages. It defines the structure and content of a page, such as headings, paragraphs, links and images.

I

Image SEO: Image SEO covers all measures that make images more understandable for search engines, image search and machine systems. This includes alt text, descriptive file names and suitable context.
Impressions: Impressions indicate how often a website's search result was shown in Google Search, regardless of whether it was clicked. They are a core Google Search Console metric and reflect a page's raw visibility for given queries.
Indexing: Indexing is the step in which a search engine processes crawled content and decides whether a URL is added to the search index. Only indexed pages can appear in search results.
Interaction to Next Paint (INP) INP: Interaction to Next Paint (INP) measures how quickly a page responds to user input across all interactions and represents interactivity.
Internal Linking: Internal linking refers to links that connect pages within the same website. They control how search engines and users find and thematically classify content.

J

JavaScript Object Notation (JSON) JSON: JavaScript Object Notation (JSON) is a lightweight, text-based data format for storing and exchanging data. It is human-readable and easy for machines to process.
JavaScript Rendering: JavaScript rendering is the process by which a browser or crawler executes JavaScript code to build the final, visible page. Content that is not already in the delivered HTML only appears after this step.
JSON-LD JSON-LD: JSON-LD (JavaScript Object Notation for Linked Data) is a data format for embedding structured data in a page, separate from the visible HTML. Google recommends it where technically possible.

K

Key Takeaways: Key takeaways are the most important insights of an article presented as a short, easily scannable list. They help users grasp central points quickly.
Keyword: A keyword is the search term users enter into a search engine to find information, products or providers. Keywords are the basis against which rankings and visibility are measured.
Keyword Cannibalization: Keyword cannibalization occurs when several pages of the same website target the same search intent and thereby compete internally for the same rankings. Google then fails to identify a clear main page.
Knowledge graph: A knowledge graph represents entities as nodes and their relationships as edges. It helps search engines and AI systems model things and how they connect.

L

Lab Data: Lab data are produced in a simulated test environment with fixed device and network conditions. They help identify the technical causes of performance problems.
Landmark Elements: Landmark elements are semantic HTML regions such as <main>, <nav>, <header> and <footer> that give a page clear orientation points, especially for screen readers.
Large Language Model (LLM) LLM: A Large Language Model (LLM) is an AI model that learns from large amounts of text and generates formulated answers from it. LLMs form the core of generative answer systems such as ChatGPT, Perplexity or Gemini.
Largest Contentful Paint (LCP) LCP: Largest Contentful Paint (LCP) measures when the largest visible content element in the viewport has loaded, representing the perceived loading speed.
lastmod: lastmod is an element in the XML sitemap indicating when a URL's main content was last significantly changed. It is only useful when maintained reliably.
Lazy Loading: Lazy loading is the deferred loading of content such as images only when it enters the visible area, in order to reduce the initial loading time.
Lighthouse: Lighthouse is an open-source diagnostic tool from Google that audits a page's performance, accessibility and other quality aspects in a simulated lab environment.
llms.txt: llms.txt is a voluntary Markdown file in a website's root directory that gives language models a compact overview of important content. It is a proposal or de facto format, not a binding official web standard.

M

Meta Description: The meta description is an HTML element in the page <head> that briefly summarises the page's content. Google can display it as the description in the search result.
Meta Robots Tag: The meta robots tag is an HTML element in a page's <head> that gives search engines indexing and link-following instructions such as noindex or nofollow.
Modification Date (dateModified) dateModified: The modification date (dateModified) is a structured data field that machine-readably indicates the last relevant content revision of an article.

N

NAP (Name, Address, Phone) NAP: NAP stands for a company's Name, Address and Phone number. Consistent NAP data across the website and external profiles is an important entity and trust signal.
nofollow Attribute: The nofollow attribute is a hint to search engines not to follow a link as an endorsement. On internal links it should be used selectively and not as a default.
noindex: noindex is a robots directive telling search engines that a page should not appear in search results. The page must remain crawlable for it to work.

O

OAI-SearchBot: OAI-SearchBot is the crawler documented by OpenAI for ChatGPT Search. It fetches content so that public websites can appear as a source in ChatGPT summaries, snippets and answers.
Open Graph OG: Open Graph is a protocol of meta tags in a page's <head> that controls how a link is displayed as a preview when shared on social networks and messengers.
Organization Schema: Organization schema describes a company or organisation as an entity, with details such as name, URL, logo, address, contact and official profiles.
Orphan Pages: Orphan pages are URLs that have no or barely any internal links pointing to them from other pages on the same website. They are hard for users and search engines to find.

P

PageSpeed / Load Time: PageSpeed refers to the loading time and responsiveness of a website. PageSpeed optimisation covers measures that improve loading time, responsiveness and visual stability.
Pay-Per-Click (PPC) PPC: Pay-Per-Click (PPC) is a billing model in online advertising where the advertiser only pays when a user actually clicks the ad. Impressions alone are free.
People Also Ask PAA: People Also Ask (PAA) is a Google SERP element that shows related questions with expandable answers. It helps users explore a topic further and can affect clicks.
Percentile: The 75th percentile is the threshold at which at least 75 % of page views reach the good value. Core Web Vitals are assessed at this point, not at the average.
PerplexityBot: PerplexityBot is the crawler documented by Perplexity, intended to make websites visible in Perplexity search results and link them as a source. According to Perplexity, it is not used to train foundation models.
Pillar Page: A pillar page is the central overview page of a topic cluster. It covers a subject broadly and links to in-depth detail pages, which in turn link back to it.

R

Ranking Volatility: Ranking volatility refers to the fluctuation of positions in the search results over time. Daily movements are normal; a stable, relevant downward trend is the real concern.
Real User Monitoring (RUM) RUM: Real User Monitoring (RUM) captures performance and experience data from real users during their actual visit. It provides so-called field data from real-world usage.
Redirect: A redirect forwards users and search engines from one URL to another. It can be permanent (301) or temporary (302) and transfers signals to the target URL.
Render-Blocking Resources: Render-blocking resources are files such as CSS or JavaScript that the browser must load and process before it can render the page, thereby delaying rendering.
Responsive Images: Responsive images deliver an appropriately sized image variant depending on the device's screen size and resolution, so that unnecessarily large files are not loaded.
Rich Results: Rich results are enhanced displays in Google, for example with ratings, prices or breadcrumbs, which can be enabled by suitable structured data.
robots.txt: The robots.txt is a publicly accessible text file in a site's root directory. It tells crawlers which URLs they may fetch and therefore controls crawling.

S

sameAs: sameAs is a Schema.org property that links an entity to reference pages confirming its identity, such as official profiles, Wikipedia or Wikidata. It serves disambiguation.
Schema Markup (Structured Data): Schema markup is code that describes a page's content in a structured way, so search engines understand it not just as text but as clearly classified information.
Search Engine Advertising (SEA) SEA: Search Engine Advertising (SEA) means paid ads in the search results, usually billed on a pay-per-click basis.
Search Engine Marketing (SEM) SEM: Search Engine Marketing (SEM) is the umbrella term for all marketing activities within search engines. It covers both paid search advertising and organic search engine optimisation.
Search Engine Optimization (SEO) SEO: Search Engine Optimization (SEO) covers all measures that help a website become more visible in unpaid (organic) search results.
Search Engine Results Page (SERP) SERP: The Search Engine Results Page (SERP) is the page a search engine returns after a query. Besides the organic listings it often contains extra elements such as ads, featured snippets or AI Overviews.
Search Intent: Search intent is the goal behind a search query: does the user want to learn something, buy something or reach a specific page? Content only ranks well if it matches this intent.
Search Visibility: Search visibility describes how present and findable a website is in the organic search results. It is not the same as traffic, but reflects theoretical findability.
Semantic HTML: Semantic HTML means using HTML elements according to their meaning, such as <main> for the main content or <nav> for navigation, instead of building everything from generic <div> containers.
Sentiment: Sentiment describes the tone in which a brand is portrayed in AI answers, for example positive, neutral, mixed, negative or uncertain. It measures the quality of a mention, not just its presence.
Server-Side Rendering (SSR) SSR: With Server-Side Rendering (SSR), the server generates the finished HTML before delivering the page to the browser or crawler. Content is therefore present in the source immediately.
Share of Voice SoV: Share of Voice in AI answers measures the proportion of mentions a brand receives within a prompt set compared to competitors. It indicates the competitive position in AI answers.
Sitemap Index: A sitemap index is a parent sitemap file that references several individual XML sitemaps. It is needed when a website exceeds the size limits of a single sitemap.
Snippet: A snippet is the compact display of a result in the search results, usually made up of a title, URL and description. It is what users see before clicking.
Soft 404: A soft 404 is a page that looks like an error page or redirects irrelevantly but technically sends status code 200. Search engines may wrongly treat it as a valid page.
Source Quality: Source quality shows whether important statements are backed by reliable evidence. It does not mean adding links indiscriminately, but providing robust support for verifiable claims.
Striking Distance Keywords: Striking-distance keywords are search terms for which a page already ranks just outside the top results, typically at average positions 5 to 20. They already earn impressions but few clicks, and count as quick wins because small optimizations often produce noticeable click gains.

T

Thin Content: Thin content is content with too little independent value. A page is thin when it fails to satisfy a search intent adequately or adds nothing substantial to existing pages.
Time to First Byte (TTFB) TTFB: Time to First Byte (TTFB) is the time until the browser receives the first byte of the server response, describing how quickly the server reacts.
Title Tag: The title tag is an HTML element in the page <head> that defines the page title. It appears in the browser tab and can be used as the clickable title in search results.
TL;DR TL;DR: TL;DR stands for "Too Long; Didn't Read" and refers to a short summary at the start of a longer text that delivers the key message immediately.
Topic Cluster: A topic cluster is a group of thematically related pages in which a central pillar page and supporting detail pages link to each other. This creates a clear topical structure.
Trust signals: Trust signals are visible elements of a website that build credibility, such as an imprint, contact details, privacy information, sources, reviews, update dates and transparent company information.

U

URL Mismatch: A URL mismatch means that for a keyword the wrong page of the website ranks instead of the intended target URL. It is especially critical when an info page appears instead of a commercial landing page.

V

Visibility Index VI: The visibility index is an SEO metric that condenses many of a domain's organic Google rankings into a single value. It shows whether search visibility is rising, stagnating or falling.

W

WebP / AVIF: WebP and AVIF are modern, space-saving image formats that produce much smaller files than JPEG or PNG at comparable quality, improving loading time.

X

X-Robots-Tag: The X-Robots-Tag is a robots directive sent in the HTTP header. It allows indexing rules such as noindex to be applied to non-HTML files like PDFs or images.
XML Sitemap XML: An XML sitemap is a machine-readable file listing a website's important URLs. It helps search engines discover content more efficiently but does not replace internal linking or guarantee indexing.

Y

Your Money or Your Life (YMYL) YMYL: YMYL (Your Money or Your Life) refers to topics affecting money, health, safety, law or important life decisions. E-E-A-T matters especially for these topics.

Z

Zero-Click Search: A zero-click search is a query where the answer appears directly in the search results and the user clicks no listing. SERP features and AI Overviews amplify this effect.