# Builds

A build is one hosted Widgetbook, tied to one Git commit.
It contains the browsable web app plus every [snapshot](/cloud/snapshots/overview) and semantics tree captured by `flutter test`.

<Image src="/assets/cloud/projects/overview.png" caption="List of builds with their corresponding commit SHA and branch" zoom />

Builds are what everything else reads from:

- The team browses any commit's Widgetbook in a browser, on a stable URL.
- A [visual pull request](/cloud/visual-pull-request/overview) diffs the `base` build against the `head` build.
- The Git commit status links to the build.
  See [Access build from Git commit](/cloud/builds/access-from-commit).

## Immutability

One build per commit SHA per branch per project.
Pushing a second build for the same SHA and branch fails once the first has uploaded and processed successfully, unless you pass `--allow-existing`, which skips the upload and reuses the existing build.
A build that failed or never finished does not block a retry.

## Status

| Status | Meaning |
| --- | --- |
| **None** | No build has been uploaded, so there is no preview. |
| **In progress** | The upload finished, snapshots are being processed. |
| **Successful** | The upload finished and all snapshots are processed. |
| **Failed** | The upload or the snapshot processing failed. |

## Next

- [Upload builds](/cloud/builds/upload) to push a build from CI or from your machine.
- [Access builds](/cloud/builds/access-from-commit) to open a build from a commit status in your Git provider.
- [Turbo Builds](/cloud/builds/turbo) to reuse a build when nothing relevant changed.