702.89a Infect is a static ability.
702.89b Damage dealt to a player by a source with infect doesn't cause that player to lose life. Rather, it causes the player to get that many poison counters. See rule 119.3.
702.89c Damage dealt to a creature by a source with infect isn't marked on that creature. Rather, it causes that many -1/-1 counters to be put on that creature. See rule 119.3.
702.89d If a permanent leaves the battlefield before an effect causes it to deal damage, its last known information is used to determine whether it had infect.
702.89e The infect rules function no matter what zone an object with infect deals damage from.
702.89f Multiple instances of infect on the same object are redundant.