Slowplaying is the act of not betting your hand so others won't
know its true strength. You are setting a trap having other players
bet when they are drawing dead or almost drawing dead. Usually a
player waits till the turn or river to spring the trap and raise
the players in the pot.
When should you slowplay?
Against poor players almost never. You should generally bet your good hands since they will call you anyways. Only when you have a table full of players that are drawing dead should you even consider slowplaying. Only against tougher players should you slowplay. You want them to bet incorrectly their hands letting them think they are ahead.
EXAMPLE: 5 callers and you call on the button with 77. The flop comes down 778. An early position player bets, 2 others call, and then the cutoff raises. At this point you can simply cold call here. Probably there is a flush draw and a straight draw out there and you want them to catch up. Your raise should probably come on the turn costing all those draws 2 big bets to draw dead vs your quads. This scenario is very rare but does occur.
7
. The flop comes down 7
7
8