Software development is still a very human oriented task. High level programing languages are some form of human readable language.
At some point you'll need to compare one or more files and see what changed.
This is a list of file and folder comparison tools that I came across at some point in time.
It's old and doesn't have many features, but it's still able to compare files and folders.
Also a free tool, WinMerge has a few more features than WinDiff.
KDiff3 is also a free tool and can handle two or three files or folders.
Unlike the others, KDiff3 is a multi platform tool.
Compare It!, from Grig Software, it's not free (unless you own a licence for ApexSQL Diff), although not very expensive. This tool can recognize a few file formats like MS Word, Excel, PDF and RTF and has syntax highlighting for C++, Java, C#, Delphi and HTML.
Merge, from Araxis, is, in my opinion, the best file and folder comparison tool in the market. Imagine that it can even compare images. It also has a Virtual File System (VFS) API and comes with plugins for Perforce and Visual SourceSafe (a TFS plugin is overdue).
It's not free, but the feature set is rich.