Visual Diff and Merge tools
Working with source controls systems implies to view differences between versions, merge changes.
Or you just want to see quickly a difference between two files or folders.
On Linux you could stick to good and old tool diff, but it's a command line tool and it gets very confusing when viewing differences between big files.
It's much better to use visual tools for these task, moreover they integrate well with source control tools like explained in one of my previous topics.