Microsoft SyncToy

There are a number of ways to backup your data, but I prefer to have an exact duplicate of my crucial data on at least two physically separate media. An easy and free way to do that (for windows users) is MS SyncToy. It allows you to sync two folder in a number of different ways.
My favorite here is "echo" in which the new and update files in one directory are synced to a second directory, Simple and efficient.