Floppy Drives are an amazing thing. In a field where EVERYTHING changes every 6 months, Floppy drives have remained basically the same for about 15 years now. But over the course of time their role has changed. At one time they were the primary method of storing and retrieving programs and files. That role has been filled by the Cd-Rom drive. Now they are used primarily to store smaller files for archival purposes or for transport from one location to another. Much has been made of the obsolescent Floppy Disk drive and there is some to truth to that. A floppy disk can hold 1.44MB of data on a single disk. That isn't much by today's standards. Almost all programs and even some basic pictures are larger than that. It's also slow, it would take about 5 minutes to transfer all the info from a Floppy Disk onto a Computer, plus the data on a floppy disk is very corruptible. So why do we still have the floppy disk drive in practically every computer? Well it all comes down to money and compatibility. You can pick up a floppy drive for 15 bucks and the 3.5" disks are less than a buck a piece. Plus your floppy disk will work in everyone else's computer. So the legacy of the slow, unreliable, obsolescent, floppy continues for one simple reason...it's just plain practical. 

Other than that, there's not too much more to know about them...other than If you did not have a hard drive you could still access your computer via the floppy drive - I recommend that all computers have one!!