Angle Shooting usually refers to using underhanded or unethical tactics in an attempt to gain an edge against opponents. This can refer to acting out of turn, hiding high value chips behind smaller ones, or pretending to put chips into the pot.
While not usually technically against the rules, angles are moves that are unfair and of poor practice.
Example 1: John purposely slides a 50,000 chip behind his 1,000 chips, so that his opponents can’t correctly determine the value of his stack.
Example 2: Eric purposely pretends to slide some chips in the middle, before pulling them back and looking at his opponent to try and gauge his reaction.