Security is mostly a superstition. It does not exist in nature… Life is either a daring adventure or nothing.
Helen Keller (The open door)
Backup is a very-very important thing in IT. The loss of code-snippets, patch-sets, configurations or documents is very painful for programmers, system administrators and secrataries.
There are many options for this, among others hand (manually) copying. There are many applications responsible for backup on Linux, Mac or Windows. Many people use rsync as lacyc3 wrote a good post about it (in Hungarian).