A puzzling omission from the Git book

I'm looking for a way of comparing the files in two branches. According to Stack Overflow there's a git diff command but I can't see any reference to it in the book. Am I being more than usually thick? The Git Gui app doesn't seem to have that command in it either. A bit frustrating. Yours,

Problems installing git-for-windows

Hi, I've just downloaded git-for-windows. It uninstalled an earlier version that I had (about 5 years old) and I got some problems. 1) It wanted to install into my User directory instead of the Program Files directory, which is the best place for all programs. The installer told me that this had