Boosting is bypassing the challenge required to earn something legitimately.
Imagine there's an Achievement for getting a Triple Kill with a Shotgun and you're having difficulty getting it. You then ask me, as a friend of yours, to find two others willing to help and stand still in a Free for All game for you to get a Triple Kill
with a shotgun on us.
We won't fight back, we won't even move. We'll even make it easier by standing right next to each other. You don't have to struggle or try to earn the achievement, just a simple invite to me and my friends, a single game and less than a minute and you've
got your Achievement.
It relates to playing in a party because you need to be in the same game to do it. You would have to send me and invite, then the other two, search in Free for All (if this was a Team Slayer Achievement, you could just party up with seven others and kill
the people on the other team) and find us, wait for us to get together and kill us.
Lol I think it's more that most of the maps in Reach suck. The popular become very boring and tiresome because they're ALWAYS in the selection screen and are ALWAYS voted for. Countdown is a decent map, but I can't stand when I get into it 4 games in a row.