Why Cargo Exists - The Cargo Book

## Why Cargo Exists

Cargo is a tool that allows Rust packages to declare their various dependencies and ensure that you’ll always get a repeatable build.

To accomplish this goal, Cargo does four things:

- Introduces two metadata files with various bits of package information.
- Fetches and builds your package’s dependencies.
- Invokes `rustc` or another build tool with the correct parameters to build your package.
- Introduces conventions to make working with Rust packages easier.