LLM Visibility Glossary

All important terms on AI search engines, llms.txt and website optimization clearly explained

A

Accessibility

Accessibility

Die Accessibility einer Website für alle Nutzer, einschließlich Menschen mit Behinderungen und KI-Bots. Wichtige Elemente sind Alt-Texte für Bilder, korrekte Überschriftenstruktur, ARIA-Labels und semantisches HTML. KI-Suchmaschinen bevorzugen barrierefreie Websites, da sie leichter zu crawlen und zu verstehen sind.

SEO

AI readiness

The degree to which a website is optimized for AI search engines like ChatGPT, Claude and Perplexity. Includes structured data, semantic HTML, clear metadata and crawlable content. An AI-ready website is better understood by AI bots and cited more frequently in AI-generated answers.

Technical

Alt text

Alternative text describing images. Read aloud by screen readers and helps AI bots understand image content. Format: <img alt="Image description">. Important for accessibility and AI readiness, as bots cannot "see" images.

Technical

ARIA labels

Accessible Rich Internet Applications — HTML attributes providing additional information for screen readers and AI bots. Example: aria-label="Search field", role="navigation". Improves semantic structure and AI comprehensibility.

B

SEO

Bot / Crawler

Automated programs that crawl and index websites. Examples: Googlebot (Google), GPTBot (ChatGPT), ClaudeBot (Claude). Bots follow links, read content and collect data for search engines or AI models. The robots.txt controls which bots have access.

Content

Breadcrumbs

Navigation path showing page structure (e.g. Home › Products › Category). Helps users and bots understand website hierarchy. Can be structured with Schema.org BreadcrumbList for better AI comprehensibility.

C

AI

ChatGPT

AI chatbot by OpenAI that crawls websites via GPTBot. Uses crawled content to answer questions. Websites can block or allow GPTBot in robots.txt. Important for AI readiness: structured data and clear content.

AI

Claude

AI assistant by Anthropic that crawls websites with ClaudeBot. Analyses content for context and answers. Prefers well-structured, accessible websites with clear metadata and Schema.org markup.

SEO

Content quality

Measure of website content quality. Factors: text length, text-code ratio, internal linking, heading structure, lists and tables. AI bots prefer substantial, well-structured content over thin pages.

SEO

Crawlability

The ability of bots to crawl a website. Influenced by robots.txt, meta tags (noindex/nofollow), sitemaps, and internal linking. Good crawlability is essential for AI readiness.

D

Technical

Disallow

Instruction in robots.txt that excludes bots from crawling certain areas. Example: "Disallow: /" blocks all bots. "Disallow: /admin/" blocks only the admin area. Critical for AI readiness: accidental blocking prevents indexing.

G

SEO

GEO (Generative Engine Optimization)

The optimization of content for AI-powered search engines and chatbots such as ChatGPT, Claude, and Perplexity. GEO goes beyond classic SEO and focuses on structured data, natural language, context, and semantic markup in order to be cited in AI-generated responses. Synonymous with AI readiness and AI visibility.

AI

Google Gemini / Bard

Google's AI chatbot uses Google Extended Bot for crawling. Integrated into Google Search. Websites can use robots.txt to control whether Google Extended has access.

AI

GPTBot

Official crawler from OpenAI for ChatGPT. User agent: "GPTBot." Can be blocked in robots.txt: "User-agent: GPTBot" + "Disallow: /." Crawls websites to collect training data and current information.

H

Technical

H1 tag

Main heading of a page (Heading 1). Best practice: exactly one H1 per page, describing the main topic. Important for SEO and AI readiness, as bots use H1 as the primary content indicator.

Accessibility

Heading hierarchy

Logical structure of headings (H1 → H2 → H3). Do not skip levels! Incorrect: H1 → H3. Correct: H1 → H2 → H3. Helps bots and screen readers understand the content structure.

Technical

HTML sitemap

Human-readable overview of all pages on a website (usually /sitemap.html). Complements the XML sitemap and improves navigation for users and bots.

K

SEO

AI visibility

Synonym für AI-Readiness. Beschreibt, wie gut eine Website von KI-Suchmaschinen wie ChatGPT, Claude und Perplexity gefunden, verstanden und zitiert wird. Faktoren: Structured Data (Schema.org), semantisches HTML, Crawlability (robots.txt), Content-Qualität und Barrierefreiheit. Im deutschen Markt der etablierte Begriff für die Optimierung auf KI-Bots.

AI

AI search engine

Search engine that uses AI to generate answers instead of just showing links. Examples: ChatGPT, Claude, Perplexity, Google Gemini. Uses web content to create natural language answers.

L

Technical

Lang attribute

HTML attribute that defines the language of a page. Format: <html lang="en">. Helps bots and screen readers recognize the correct language. Important for international SEO.

LLM Visibility

llms.txt

Text file in Markdown format in the root directory of a website (yourdomain.com/llms.txt). Provides AI systems like ChatGPT, Claude and Perplexity with structured information about the website — similar to robots.txt for crawlers, but as a content description. Proposed in 2024 by Jeremy Howard, officially supported by Anthropic. Currently fewer than 1% of all websites have an llms.txt. Learn more in the llms.txt Guide.

LLM Visibility

llms-full.txt

Optional extension to llms.txt. Contains the complete content of the most important pages in a form optimised for LLMs — as a single readable file. Particularly useful for documentation sites and knowledge bases. For most websites, llms.txt is the more important first step.

AI

LLM (Large Language Model)

Large Language Model — the AI technology behind chatbots like ChatGPT, Claude and Gemini. LLMs are trained on vast amounts of text and can understand and generate natural language. The foundation for AI search engines and AI assistants.

M

SEO

Meta description

Short description of a page in the HTML head. Displayed in search results. Optimal: 150–160 characters. Important for click-through rate, also helps AI bots understand the page content.

Technical

Meta tag

HTML element in the <head> that provides meta information. Examples: description, keywords, robots, viewport. Meta tags control how bots treat the page (index/do not index).

N

Technical

NOINDEX

Meta tag that instructs search engines NOT to index a page. Format: <meta name="robots" content="noindex">. CRITICAL: Prevents the page from appearing in search results. Common mistake in AI readiness!

Technical

NOFOLLOW

Instruction to bots not to follow links on a page. As a meta tag: <meta name="robots" content="nofollow"> or link attribute: <a rel="nofollow">. Prevents link authority from being passed on.

O

SEO

Open Graph

Meta tags for social media sharing (Facebook, LinkedIn). Format: og:title, og:description, og:image. Controls how links are displayed on social media. Improves presentation when sharing.

P

AI

Perplexity

AI search engine that crawls websites with PerplexityBot. Specializes in fact-based answers with source references. Often cites well-structured websites with clear data.

R

Technical

robots.txt

Text file in the root directory (/robots.txt) that defines crawling rules for bots. Controls which areas may be crawled. Critical for AI readiness: "Disallow: /" blocks ALL bots!

Content

RSS feed

XML format for content updates (Really Simple Syndication). Enables automatic content distribution. Helps bots discover new content quickly. Format: application/rss+xml or application/atom+xml.

S

SEO

Schema.org

Vocabulary for structured data on the web. Defines types such as Article, Product, Organization. Embedded in JSON-LD, Microdata, or RDFa. Essential for AI readiness — helps bots understand content semantically.

SEO

SEO (Search Engine Optimization)

Optimization of a website for search engines. Includes on-page (content, meta tags, structure) and off-page (backlinks) measures. Basis for AI readiness, but AI optimization goes beyond this (structured data, semantic HTML).

Technical

Sitemap

XML file that lists all URLs of a website (usually /sitemap.xml). Helps search engines find and index pages. Submitted in robots.txt or Google Search Console. Important for complete indexing.

Structured Data

Structured Data

Machine-readable data in the code that describes content semantically. Formats: JSON-LD (preferred), Microdata, RDFa. Uses Schema.org vocabulary. Enables rich snippets in search engines and better AI understanding.

T

SEO

Title tag

Title of a page in the HTML head. Displayed in browser tabs and search results. Optimal: 50–60 characters. Most important on-page SEO factor. Should contain the main keyword and encourage clicks.

U

Technical

User agent

Identifier sent by a bot or browser. Examples: "Googlebot", "GPTBot", "ClaudeBot". Used in robots.txt to control specific bots. Important: Define each bot individually in robots.txt!

W

Technical

Wildcards (*)

Placeholders in robots.txt for multiple URLs. User-agent: * = all bots. Disallow: /*.pdf = all PDF files. Useful for efficient crawling rules.

X

Technical

XML sitemap

Machine-readable sitemap format for search engines (/sitemap.xml). Contains URLs, last modification, priority. Helps bots find all pages. Should be linked in robots.txt: "Sitemap: https://example.com/sitemap.xml"