All *nix machines have the feature allowing you to compare two files --often useful to do a quick 'cmp' or 'diff' on the cli for a file comparision --a good feature for a small script file or documents. However, if you want to compare chunks of code, between two versions, then the readability isnt optimal.

Meld to the rescue!

Meld is a visual diff and merge tool which allows you to compare two or three files located in different directory paths on your local machine and edit them. It allows comparison of upto three folders.

I love useful software written in Python using the PyGTK toolkit. Meld has been packaged for Ubuntu and "sudo apt-get-install meld" would install this small utility which can be accessed via: Application >Programming >Meld Diff Viewer.

Its that simple.