+++
title="Distribution API"
aliases=[
  "/docs/reference/distribution-api/"
]
+++

This specification defines the artifact format, delivery mechanism, and order resolution process for buildpacks.

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## Buildpack Descriptor

A buildpack must contain a `buildpack.toml` file in its root directory.

## Buildpackage

A buildpackage is a distributable artifact that contains a buildpack. Its format may be either:

* An OCI image
* An uncompressed tar archive with the extension `.cnb` containing an OCI image.

## Further Reading

You can read the complete [Distribution specification on Github](https://github.com/buildpacks/spec/blob/main/distribution.md).