# Concepts

> Projects, Project IDs, buckets, objects, the code tree, refs, events and backups.

## Projects and the Project ID

A **project** groups related buckets: an app, a client, a monorepo. Each project has a **Project ID** that starts with `cbp_`, like `cbp_4k9x2m7q1n8v3c6z0b5w`. It never changes, and it's how the API addresses the project (`/v1/projects/{project_id}/…`). The Console shows it with a copy button on the project page.

An account can have up to 100 projects.

## Buckets

A **bucket** lives in one project and holds your code and assets, up to **10 GB**. Its id starts with `cbk_`. Each bucket has:

- its own **encryption key** for everything stored in it ([Encryption](/code-buckets/encryption)),
- **stored objects**: the zips and assets you uploaded,
- a **code tree** built from your latest zip, for [preview](/code-buckets/preview),
- an **events** feed and **backups**.

A project can have up to 100 buckets.

## Objects: archives and assets

Everything you upload becomes an **object** (`cbo_…`):

| Kind | What it is | What happens |
| --- | --- | --- |
| `archive` | A `.zip` of code | Stored encrypted, and unpacked into the bucket's code tree (when preview is on) |
| `asset` | Any other file: images, builds, datasets, videos | Stored encrypted, downloadable as is |

Objects count toward the bucket's 10 GB. Deleting one frees its space.

## The code tree and refs

When a zip finishes uploading, Code Buckets unpacks it into the bucket's **code tree**. Each version of the tree has a **ref**: a 40-character id like `9b1f0c5e2a7d43e8b6c1f0a9d2e5b7c4a1f3e8d0`.

- `bucket.code.ref` is the current version.
- `code.updated` events and backups record the ref they produced or captured.
- Reading with an explicit `?ref=` always returns the same content, so those responses are cached and fast.

A zip replaces the whole tree, or only one folder if you upload it with `target_path` (like `packages/api`).

## Events

Code Buckets has no comments or threads. Instead every action is an **event** (`cbe_…`) in an ordered feed: uploads, code changes, deletions, backups, restores, settings changes and key actions, each with who did it (which API key, or the Console). See [Events](/code-buckets/events).

## Backups

A **backup** (`cbb_…`) captures a bucket's code tree and the list of its stored objects. Restoring puts that tree back as a new version and brings back objects deleted since. See [Backups](/code-buckets/backups).

## Tokens

Code Buckets usage is counted in **tokens**: 1 per API request, plus 1 per MiB uploaded or downloaded. The Free tier includes 1,000,000 a month. See [Pricing](/code-buckets/pricing).

## IDs at a glance

| Prefix | What |
| --- | --- |
| `cbp_` | Project (the Project ID) |
| `cbk_` | Bucket |
| `cbo_` | Upload / stored object |
| `cbe_` | Event |
| `cbb_` | Backup |
| `CL-` | Your Account ID |