Solid State Drives (SSDs) are the new hotness - well, not even really that new anymore. Traditionally, desktop and laptop computers use a hard disk drive to store the operating system and other data. These electro-mechanical disk devices are subject to wear and tear, and will eventually fail. WILL, not MAY.
SSDs have no mechanical parts to wear out, operate at cooler temperatures and use less power that the "old" hard disks. They are also noticeably faster in operation, and can make an older computer feel new again. However, they also have a limited lifespan due to the nature of their construction and operation.
Briefly (this is not a technical deconstruction of Solid State Drives by any means), the NAND flash memory that is used in most SSDs has an expected finite number of P/E (Program/Erase) cycles that each "cell" of the memory can handle. Each time data is written to a particular cell, one of those finite cycles is used up.
The actual number of P/E cycles varies by what specific kind of NAND memory is used. It can be several hundreds or several thousands of times, and while that may not sound like a lot, the drives use electronics to "even out" the wear and tear on the cells across the whole drive.
This is important, as one way to maximize the life of your SSD drive is to try to avoid "filling" up the drive - a drive using close to it's total storage capacity will eat up it's P/E cycles quicker, as the wear and tear cannot be spread out as effectively.
Simply put, if you have a 120GB SSD and habitually use 90GB of it's capacity, that drive would mathematically be expected to fail sooner than the same device using 75GB of it's capacity on a regular basis (all other things being equal). Even more simply, try to by the largest capacity SSD drive you can reasonably afford.
Glad to say, "failing sooner" is a relative term, and current SSDs should last as long as the other hardware in your computer, barring some kind of random electronic failure. Of course with ANY computer you should back up your stuff on some kind of a regular schedule, that's just common sense.
I would also recommend using an uninterruptible power supply ("UPS") with a desktop PC using an SSD, as they have been shown not to handle power surges or sudden power interruptions well.
Lest you are in any doubt about SSD drives, this old IT guy has SSDs in all three computers in our home; the home workhorse, my laptop and a small media center PC. They made a wonderful performance difference in all 3 computers and I have no hesitation in recommending them to anyone who asks me.
Some online help with upgrading to an SSD: