---
title: Concepts
description: Understand resources, retrieval, access, and asynchronous completion.
doc_version: 0.1.0-preview
last_updated: 2026-09-14
---

# Concepts

Learn the resource model from the outside in. A cluster contains namespaces, namespaces contain collections, and collections contain files. Keys control application access. Access rules control the content available to each reader.

## The resource model

*Illustration: Namespaces separate tenants inside a cluster. Collections group related files within each namespace. A retrieval request addresses one collection.*

Start with [Clusters and namespaces](/engine/concepts/clusters). Then read [Collections](/engine/concepts/collections) and [Files and paths](/engine/concepts/files). These chapters explain the objects you create and the identifiers you use in URLs.

## The content lifecycle

A source supplies file bytes. Processing makes those bytes available for retrieval. [Sources and processing](/engine/concepts/processing) explains source choices and observable states. [Jobs and events](/engine/concepts/jobs) explains when an accepted request actually finishes.

*Illustration: Content moves from a source to a processing file, then to a ready file. The status tells your application when retrieval can use it.*

## Retrieval and access

[Search and Query](/engine/concepts/retrieval) explains evidence, answers, and citations. [Keys and actions](/engine/concepts/keys) explains what your application can call. [Principals and access rules](/engine/concepts/access) explains which files a person can retrieve.

*Illustration: An API key combines a resource scope with permitted actions. Your application separately supplies principals for retrieval in an enforced collection.*

Use the [Glossary](/engine/glossary) for a short definition. Use [Get started](/engine/get-started) to put these concepts into one working flow.
## Sitemap

See the full [sitemap](/sitemap.md) for all pages.