Git lets you work without connecting to the Internet. Eventually, you'll want to share your work.
There are two ways to do this, creating a patch or pushing your new code to the master repository.
Making a patch...
A patch file is a description of the changes that have been committed. Another developer can apply your patch files to their code to use your new code.
The format-patch command will collect your changes and create one or more patch files. The patch files will be named with a number, a description and .patch.