Freeroll is a tournament with no entry fee, so it is the best way to practice poker without risk and get some extra cash in addition to your free poker cash. As the prizepool of freerolls are usually around few hundred dollars and the number of players is always several thousands therefore its difficult to end up in the money. Most of the time only first few places pay well. However freerolls do not have an entry fee but in most cases you have to be a real money player to be able to take part in these tournaments. There could be some other specific restrictions as well, like: "new players' freeroll" , invitational freerolls, country specific freerolls.

Make sure that you check out the following main freerolls (first you have to sign up for a free poker cash bankroll at these sites)

Weekly $1000 Freeroll at CD Poker for Poker Room School players

Poker Strategy Freerolls for only PS players at Party Poker, Titan Poker or Mansion Poker

Monthly $250 Freerolls for Your Poker Cash players at Ultimatebet and Absolute Poker