About the "new" slang that's out there...?

Okay, maybe I'm dating myself here, but I need a couple of definitions for some new slang I've been seeing on the Internet. I need to know in order to better understand and answer some of the questions. (Okay, yeah, I guess I'm mainly curious, too!) Okay, here goes:

1) What, or who is an "emo" ?

2) I never heard of this one until a couple of days ago, then suddenly it appeared 3 times in one day!--what does it mean when someone says they want to "snog" someone? (Is it what we used to call "make out" or something similar?)

Any knowledgeable help would be greatly appreciated. Thanks in advance!