usb 2 or 3, firewire.....thunderbolt???
I'm looking for a new external hard drive and I realize I need to know whether I neet usb 2 or 3. Or does this matter? How do I know? And firewire? In the last few years it seems they've changed their plugs a couple times. And now online I'm seeing apple "Thunderbolt". Too many options. What do I need to know? My software is up to date Mavericks. My iMac is second release of the all aluminum style of the large flatscreen iMac, it's about 7 years old I think.
iMac, OS X Mavericks (10.9.1)