How do patches work in Git?

The easiest method to create patches from the last commit (or last few commits) is to use format-patch with a negative number indicating the number of commits to create patches for:

git format-patch -1

You'll get a patch file named after the commit description. The use am to insert it into another repository:

git am << name_of_patch_file

Create your patch via:

$ git format-patch master --stdout > patch.diff

then patch.diff will contain the diff, which you can then send to someone else to apply using:

$ git am < patch.diff

Sometimes, when the manuals are a little dense, it makes sense to look for a tutorial:

http://luhman.org/blog/2009/09/22/git-patch-tutorial