Back up uses for a 2.5" external hard drive

Google some answers, think of some using your logic, there are many benefits that are simple and obvious such as back ups that can be stored in a remote location, extend your disk space in your computer by storing less used data on the external dirve etc.

But a random thought today was what the hell would happen if my homework/project was trapped on a broken or disabled laptop? and you didn't have a back up on another disk or it was not updated? that's where the external hard drive comes in, most if not all laptops use the 2.5" hard drives and then can be unplugged from the laptop and connected into the external hard drive holder, if you brought a already made external hard drive you may not be able to disconnect your hard drive but if you brought the hard drive and the external case seperate then you are pretty much able to rescue your data from the laptop hard drive,

Now for the software part, some laptop hard drives are locked into the hard drive via serial codes and pins numbers? maybe not sure but IBM hard drives are rendered useless if you just unplugged them from a laptop and tried to steal data (which is good for anti-theft purposes but for that major project deadline? dam)

Anyone got any advice for this? would be very appreciated as I am doing all my work on a laptop, my current solution is to back up recent work on a thumb drive and back up the whole data drive onto an external hard drive.