What are Death Eaters?

[dizzygurl1234 <emilygoo@angelfire.com>]

No: HPFGUIDX 49384

Hi!
  I'm sort of a latecomer to the whole HP world - after a long (and 
confusing, for my part) discussion about HP which lead to the 
discovery that I had no clue about anything, my friend forced me to 
read the entire series and watch the first movie...although it took 
some convincing since I'm not really into fantasy stuff.

  It's been a like two weeks since I read the last book - this in 
addition to the fact that I never pick up on details (no matter how 
obvious), so hopefully someone will gently nudge me in the right 
direction.  How does the whole Death Eater thing work (especially 
with Snape and Lucius) and how come Lucius isn't in trouble or 
anything for still being a DE?  You can also feel free to tell me 
about anything relating to HP - maybe I'll know what my friend is 
talking about next time! Thanks!