# Web search API glossary

> Grounding, SERP, tool calling, MCP, RAG, robots.txt, x402 and 28 more terms of web search for AI agents, explained in plain English by LLMWebSearch.

- URL: https://llmwebsearch.com/glossary/
- Last updated: 2026-10-22
- Publisher: LLMWebSearch (https://llmwebsearch.com)

The vocabulary you meet when you give an AI agent access to the web, grouped by where it comes from: search, page reading, AI models, and billing.

**Quick answer — What do the main web search API terms mean?**

A **web search API** lets a program run a search and get results as data. For AI agents, the useful part is **grounding**: giving the model current sources to answer from. **LLMWebSearch** returns ranked results with the top pages already read as **Markdown**, bills one **credit** per search from $1.20/1K searches as of October 2026, and follows **robots.txt**. The 35 terms below explain the rest.

## Search terms

**Web search API** — An interface that runs a web search on request and returns the results as structured data, usually JSON, instead of a page made for human eyes.

**SERP** — Search engine results page: what a search engine shows for a query. A SERP API returns that page as data, without reading the pages it lists.

**Ranked results** — The list of pages a search returns, in the order the engine judged most relevant. LLMWebSearch keeps that order and numbers each result with `position`.

**Snippet** — The short extract under each result's title. Useful for choosing what to read, too short to answer most questions on its own.

**Query** — The words sent to the search. Agents often rewrite a user's question into one or more shorter queries before searching.

**Search operator** — A special token inside a query, such as quotes for an exact phrase or `site:` to stay on one domain. The `q` parameter passes them through as written.

**Live search** — A search run at the moment of the request, as opposed to a lookup in an index built earlier. Results come from a live web search run at the moment of your call, in the order the search engine ranks them; nothing is served from an old index.

**News search** — A search limited to news articles, usually with dates. Set `topic` to `news`, and add `time_range` to keep only recent stories.

**Domain filter** — A rule that keeps results to some sites or removes others. The `include_domains` and `exclude_domains` parameters take up to 20 domains each.

## Page reading terms

**Page reader** — The part of the service that opens the top result pages and extracts their text. Ours introduces itself as `LLMWebSearch/1.0 (+https://llmwebsearch.com/bot/)`; the [page reader page](https://llmwebsearch.com/bot/) describes it.

**User agent** — The name a client sends with every web request. A reader that states its real name lets site owners recognise it and set rules for it.

**robots.txt** — A text file at the root of a website that tells robots which paths they may fetch. The standard is RFC 9309. Our reader respects robots.txt: it introduces itself as LLMWebSearch, follows the rules a site writes for it or for all robots, and leaves out the content of any page it is not allowed to read.

**Content Signals** — Lines in robots.txt that state how content may be used, for example `ai-input=no` to refuse use as AI input. A site that sets Content-Signal: ai-input=no in its robots.txt keeps its pages out of your results' content.

**Main-content extraction** — Keeping the article or documentation text of a page and dropping menus, footers, cookie banners and ads, so a model reads what matters.

**Markdown** — A light text format where `#` marks a heading and `-` a list item. Models read it well, and it costs fewer tokens than HTML for the same page.

**Headless browser** — A browser with no window, driven by code. It lets the reader see the text of pages that only appear after JavaScript runs.

**Paywall** — A gate that keeps content for paying subscribers. The reader never signs in and never works around a paywall; such pages come back without content.

**content_status** — The field that says whether a result's page was read and, if not, why: `ok`, `not_requested`, `blocked_by_robots`, `target_refused` and others listed in the docs.

## AI terms

**LLM** — Large language model: a model trained on text that writes text. Its knowledge stops at a training date, which is why it needs search for anything recent.

**Grounding** — Giving a model sources to base its answer on, then asking it to cite them. Search results with page text are the most common way to ground on the web.

**Tool calling** — Also called function calling. The model asks to run a tool, such as `web_search`, with arguments it chooses; your code runs it and returns the output.

**MCP** — Model Context Protocol: an open standard for exposing tools to AI clients such as Claude Desktop or Cursor. A small MCP server can wrap a search API as a tool.

**AI agent** — A program where a model decides the next step, calls tools, reads their results and repeats until the task is done. Web search is often its first tool.

**RAG** — Retrieval-augmented generation: fetch relevant text first, put it in the prompt, then generate. With a web search API, the retrieval step is the live web.

**Deep research** — An agent pattern that plans many queries, reads many pages and writes a report with citations. It can run dozens of searches for one question.

**Context window** — The amount of text a model can take in at once, measured in tokens. Set `max_chars` to cap how much of each page enters that window.

**Token** — The unit models read and bill by, roughly a short word or part of one. Clean Markdown spends fewer tokens than raw HTML.

**Citation** — A link from a statement in an answer to the source it came from. Returning sources rather than a written answer lets your model cite exactly what it read.

**Hallucination** — A confident statement a model makes up. Grounding on fresh sources and asking for citations reduces it; it does not remove it.

## Billing and account terms

**Credit** — What each call spends. One credit pays for one search: up to 20 ranked results, with the pages of the first 3 read and returned as Markdown. Reading 4 to 10 pages makes it 2 credits. A call that ends in an error costs nothing.

**Credit pack** — A prepaid batch of credits, from 5,000 searches to 1,000,000 searches. Search credits have no expiry date: what you do not use this month is still there next year.

**Top-up** — A crypto payment that funds your balance, at least $25. Packs are then bought from the balance.

**Rate limit** — The number of calls an account may make per minute. Every account has a per-minute call limit, shown in the dashboard; ask support and it can be raised.

**x402** — A protocol that lets a client pay for one HTTP request in a stablecoin, with no account. Some search APIs accept it; LLMWebSearch is paid from a prepaid balance instead.

**KYC** — Know your customer: identity checks such as an ID document or a selfie. LLMWebSearch asks for none; the [no-KYC page](https://llmwebsearch.com/no-kyc-search-api/) explains what still applies.

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LLMWebSearch: LLMWebSearch is a web search API for AI agents that returns ranked results with the content of the top pages in Markdown, paid in crypto with no ID upload. Prepaid credits from $1.20/1K searches never expire. No KYC — no ID, no selfie, no documents. Pay in crypto.