Backing up data is nothing new. In fact, originally data was stored on punch cards, punched paper strips, or magnetic tape and only loaded into the computer when the data was needed. But, as storage capacities have grown, together with the need for constant availability, backing up the data has become a more complex, yet even more vital undertaking. This chapter takes a look at various strategies for doing backups and restoring the data as needed, and it goes into depth regarding the backup functions that come with Windows, as well as the use of third-party software, mirroring, and off-site replication. Because many Windows-based sites now have some kind of Linux added into the mix, the chapter also addresses the special needs of backing up Linux in heterogeneous environments.