SSD – solid state drive, a type of storage device.
Because you are reading this blog (from “web log”), you are using the internet and have therefore probably heard of a hard drive. That’s the relatively heavy, rectangular thing inside your computer where all of your permanent data is stored. Round magnetic platters spin really fast while a little arm with a miniscule sensor on the end drifts over the spinning platters, using magnetism to read and write (change) the magnetic state of the tiny sections of the platters. The hard drive was invented in 1956, and although it is mind boggling how much the technology has improved, the whole spinning disc with a mechanical arm thing really slows things down.
This is where SSDs come in. They don’t involve any of that mechanical mumbo jumbo. Bear with me for a second here because I’d rather not create an awful analogy to explain the real magic that happens inside an SSD. An SSD has a lot of floating gate transistors in it. Unlike normal transistors, which are basically switches, a floating gate transistor traps electrons and then manipulates the charge of those electrons to make them represent 1s and 0s, the on/off mentality that computer logic is based upon. In a nutshell, the purely electronic function of an SSD allows it to be much faster than its mechanical counterpart, the hard drive.
the whole spinning disc with a mechanical arm thing really slows things down
Smaller computers like the iPad, smartphones, and the MacBook Air use SSDs. Solid state drives are becoming increasingly popular in normal laptops and even desktop computers as well, as upgrading from a hard drive provides a noticeable speed increase.
Here’s an article that does a really great job of getting into the technical differences between hard drives and solid state drives – http://arstechnica.com/information-technology/2012/06/inside-the-ssd-revolution-how-solid-state-disks-really-work/