The often overlooked Xcode FileMerge app lets you spot what's changed between two files. Here's how to spot the differences using the tool.

CSDiff will do it, and is free. It can compare directories or file contents and show you the differences. It's a few years old but I've never had any problems using it on Windows 7.

If you repeatedly revise a Word document and save it as a separate file, it is difficult to keep track of the changes. We will show you how to display the changed passages.