git-scm.com
Bundling
7.10 Debugging with Git; 7.11 Submodules; 7.12 Bundling; 7.13 Replace; 7.14 Credential Storage; 7.15 Summary; 8. Customizing Git. 8.1 Git Configuration; 8.2 ... Git is capable of "bundling" its data into a single file. This can be useful in various scenarios. Maybe your network is down and you want to send changes to your co-workers.
Submodule
The given URL is recorded into .gitmodules for use by subsequent users cloning the superproject. If the URL is given relative to the superproject's repository, the presumption is the superproject and submodule repositories will be kept together in the same relative location, and only the superproject's URL needs to be provided. git-submodule will correctly locate the submodule using the ...
Submodules
The init and update subcommands of git submodule will maintain submodules checked out and at an appropriate revision in your working tree. Alternatively you can set submodule.recurse to have checkout recurse into submodules (note that submodule.recurse also affects other Git commands, see git-config[1] for a complete list).