Party Poker is the largest of the online poker rooms. They are a PartyGaming site. (In the past, people logging on through Party Poker and through other PartyGaming "skins" could play at the same tables, but that ended in late 2005.)
PartyPoker has more specialty games than any other skin, including BadBeatJackpot tables, HighHandJackpot tables, and many specialty tournaments, such as the PartyPokerMillion cruise/tournament.
Read PlayParty to know why we think you should play there.