Angle shooting is engaging in actions that can be within the scope of the game rules but that are considered bad or unfair to take benefit of another player. An angle shooter might believe as if he were folding his hand to make other poker players induced to fold theirs out of turn.
One way of angle shooting that is exclusive to online poker is to abuse the disconnect rules most sites have. DP is a rule that is exclusive to online poker in case a player is disconnected from the site in the middle of the hand. angle

Online poker rooms provide DP and have specific tables set aside for this so that all players at the table know that the special DP rules will apply. This is used by angle shooters if a player is in hand that he is not sure if he has the finest cards and does not wait for the hand to play.