PS3 Trophies/achievements... or whatever they are?

[selnor]

The Fury said:
Okay, here's another question for you (as I'd like to know). What exactly is the appeal of these trophies things? Do they get me anything other then some kind of recognition so people can see I've completed MGS4 in 2 hours or something? Or that I found the secret mystical item in Gran Turismo?

Tell me about what they are for exactly.

Some people may not like it. But personally it's one of the best innovations for the pure reason that before achievements I may have finished a game and never played it again. Wheras now I will happily play through 2 or 3 times. My £40 spent on a game is much more worth it now.