From GIT documentation: Git Docs
Below gives the full information. In short, simple
will only push the current working branch
and even then only if it also has the same name on the remote. This is a very good setting for beginners and will become the default in GIT 2.0
Whereas matching
will push all branches locally that have the same name on the remote. (Without regard to your current working branch ). This means potentially many different branches will be pushed, including those that you might not even want to share.
In my personal usage, I generally use a different option: current
which pushes the current working branch, (because I always branch for any changes). But for a beginner I'd suggest simple
push.default
Defines the action git push should take if no refspec is
explicitly given. Different values are well-suited for specific
workflows; for instance, in a purely central workflow (i.e. the fetch
source is equal to the push destination), upstream is probably what
you want. Possible values are:
nothing - do not push anything (error out) unless a refspec is
explicitly given. This is primarily meant for people who want to avoid
mistakes by always being explicit.
current - push the current branch to update a branch with the same
name on the receiving end. Works in both central and non-central
workflows.
upstream - push the current branch back to the branch whose changes
are usually integrated into the current branch (which is called
@{upstream}). This mode only makes sense if you are pushing to the
same repository you would normally pull from (i.e. central workflow).
simple - in centralized workflow, work like upstream with an added
safety to refuse to push if the upstream branch's name is different
from the local one.
When pushing to a remote that is different from the remote you
normally pull from, work as current. This is the safest option and is
suited for beginners.
This mode will become the default in Git 2.0.
matching - push all branches having the same name on both ends. This
makes the repository you are pushing to remember the set of branches
that will be pushed out (e.g. if you always push maint and master
there and no other branches, the repository you push to will have
these two branches, and your local maint and master will be pushed
there).
To use this mode effectively, you have to make sure all the branches
you would push out are ready to be pushed out before running git push,
as the whole point of this mode is to allow you to push all of the
branches in one go. If you usually finish work on only one branch and
push out the result, while other branches are unfinished, this mode is
not for you. Also this mode is not suitable for pushing into a shared
central repository, as other people may add new branches there, or
update the tip of existing branches outside your control.
This is currently the default, but Git 2.0 will change the default to
simple.
pull.default
is available for updating all those branches locally – Nogurenn