Actually, they are not in everything.  Plenty of your stuff has a good old-fashioned harddrive in it.  However, your MP3 player (not ipods), your digital camera, and even your cell phone might be remembering for you on flash memory.  So why not learn a snippet or two about flash memory and SD cards?  

What you need to know:

Despite my introductory bravado, there isn’t much that you need to know about an SD card.  You should understand that it’s something called non-volatile memory, so it doesn’t need power to remember what you stored on it.  Also, it’s faster than a hard drive, because it doesn’t have any moving parts (it kinda zaps the information onto electric switches – this is called Sold State).  This whole solid state thing is good for battery life too. SD cards are also pretty hardy. If you drop your card, it’s going to be ok…  A harddrive has moving parts that get damaged easily (try-please don’t- dropping your ibook).  SD cards don’t (almost) bounce in comparison…

The only thing you have to remember:

SD memory is hardy but not invincible!  Your SD card has a predetermined lifespan (like anything else), measured in writes/reads/cycles.   Your card might last 10 years of hard use, but it probably won’t (after a year I’d start being cautious).   The point to remember? Backup your cards often! 

Want to know a ton more than this cocktail party geek could provide?  Try this link from howstuffworks or this one from pcstats about protecting your flash data.

~ab