Many sites offer regular freeroll events to attract new players and encourage existing players to return to the site on a regular basis. These may be either ‘true’ freerolls with no entry conditions whatsoever, or perks for players who have already provided the cardroom with a certain amount of patronage (typically measured by the number of raked hands in which they have participated).
The challenge for the cardroom is to structure these freeroll tournaments in such a way that they are attractive enough for players to visit the site, but not so attractive that their clientele will spend all their poker sessions playing freerolls at the expense of raked ring games or buy-in tournaments! Undoubtedly, some players who play in freeroll tournaments do so with no intention of ever depositing any cash to play in real money games, but even these players have some value to the cardroom, since they may encourage their friends to join the site, and those players may then make deposits and in turn encourage their own friends to sign up. A true freeroll tournament at, for example, PokerStars will attract 250-500 players, offering newcomers an ideal introduction to online tournament play.
There are two contrasting ways of approaching a freeroll event – you can either try and play your best game, treating it as a serious exercise, or you can decide to take lots of risks early on, figuring that you could get lucky and amass a ton of chips, but if you bust out you haven’t lost anything anyway!