# Key concepts

Company, signal, lead, and the credits each one spends.

Four words cover the API. The same words are what you say to an assistant.

## Company

A **company** is the employer, looked up by name (`lookup_company`, `GET /companies/lookup`, free) or enriched with firmographics (`POST /company/enrich`, **1 credit** when a company is found). You start here when you already know who you sell to.

## Signal

A **signal** is a buying moment: a funding round, a new role, a post, a technology, an event, people reacting to a company page. `search_signals` and `POST /searches` run one. A monitor keeps listening for new posts with your keywords; any other signal you follow by running its search again. The company did the thing, or a person did. The wording in the result keeps those apart.

## Lead

A **lead** is a person: someone a signal search returned (they reacted, posted or started a new role), or someone returned for a role, a seniority or a department at a company you named (`company_leads`, `POST /leads`). A person from a signal search is **1 credit**, a person from `company_leads` **1 credit**. Those rows use `per_` ids. No AI judged them: each row carries why it showed up (the post, the comment, the new role, the company you named), and your assistant decides who fits before it enriches anyone.

## Credits

**Credits** are the shared balance for the app, MCP and REST. You pay for a row that comes back. A preview (`preview_cost`, and the `/preview` routes) is free and returns the worst case, including `max_credits`. The table is [Credits & costs](/docs/api/credits-and-limits).