Diff

In computing, diff is a file comparison utility that outputs the differences between two files. It is typically used to show the changes between one version of a file and a former version of the same file. Diff displays the changes made per line for text files. Modern implementations also support binary files. The output is called a "diff", or a patch, since the output can be applied with the Unix program patch. The output of similar file comparison utilities are also called a "diff"; like the use of the word "grep" for describing the act of searching, the word diff is used in jargon as a verb for calculating any difference.