To use the Yocto Project for development, you need a release locally installed on your development system. This locally installed set of files is referred to as the Source Directory in the Yocto Project documentation.
The preferred method of creating your Source Directory is by using
Git to clone a local
copy of the upstream poky
repository.
Working from a cloned copy of the upstream repository allows you
to contribute back into the Yocto Project or to simply work with
the latest software on a development branch.
Because Git maintains and creates an upstream repository with
a complete history of changes and you are working with a local
clone of that repository, you have access to all the Yocto
Project development branches and tag names used in the upstream
repository.