Observe your Repository

Show the commit history for the currently active branch

$ git log

Show the commits on branchA that are not on branchB

$ git log branchB..branchA

Show the commits that changed file, even across renames

$ git log --follow [file]

Show the diff of what is in branchA that is not in branchB

$ git diff branchB...branchA

Show any object in Git in human-readable format

$ git show [SHA]