Git lets you see the commit messages in several ways using the git log command but sometimes that is not enough.
To see a simple one line listing with the last few digits of the commit hash, use
git log --oneline
To see an tree of the branches made using ascii, use
git log --graph --oneline --decorate --all
If you are on a mac/windows, one of the easiest ways to visualize the trees is using the extremely rich built in visual tool — gitk.