Review changes

Changes on (local) working tree

Display changes between index and working tree (what is not yet staged for commit):

$ git diff

Display changes between index and last commit (what you have staged for commit):

$ git diff --cached

Display changes in working tree since last commit (changes that are staged as well as ones that are not):

$ git diff HEAD

Use any git-ref to compare changes between two commits on the current branch.

Display changes between commit before last and last commit:

$ git diff HEAD^ HEAD

Display changes between two commits using their hashes:

$ git diff e2f404c 7977169

Display changes between tip of topic branch and tip of master branch:

$ git diff topic master

Display changes that have occurred on master branch since topic branch was created:

$ git diff topic...master

Display changes you've committed so far since creating a branch from upstream/master:

$ git diff upstream/master...HEAD