Universal Serial Bus (or USB) is a versatile interface that's used in all sorts of devices — from smartphones to lifestyle products — to deliver data, power, and video signals. Most commonly, we see ...

You probably own it and have used it—but you've never once thought about it.

I think I've seen both eg the more typical 5 pin on most Cameras MP3 players etc and then the 4 pin that comes on the Pentax Optio S4 for example.