If you're in the command line and you just want to see the history of commits without going through the hassle of either firing up a Git GUI, or seeing a full commit message for each commit you can show simplified output:
git log --oneline
This shows you a list of commits for the current tag in a simplified form - just the short sha of the commit and the first line of the commit message.
It shows all the commits - you can further shorten this with:
git log --oneline -3
which will show you the last three commits..
Simple Graph Output
git log --oneline --graph --decorate
This shows a simple history output as above - but in graphical form - so you can see the merges that have happened on the branch.