Cargo.toml is Cargo's configuration file for packages. It contains several sections.
The dependencies section ([dependencies]) contains the dependencies for the package. For example:
[dependencies]
rand = "0.8.3"This will import the rand external crate with the version number of 0.8.X where "X" is 3 or greater. The last number if considered a minor release. Any release with the same first and secondary number will have the same public API and will be compatible.
Profiles allows you to customize how your code is compiled during development and release times. Example:
[profile.dev]
opt-level = 0