How does a touch work, and what happens on the sixth touch?

• A touch is any contact between the player in possession and a defending player, including contact on the ball, hair or clothing. It can be made by the defender or by the player in possession.
• A team is entitled to six touches before a change of possession. After the sixth touch the ball goes to the other team, which restarts with a rollball at the mark.
• After a change of possession the ball must be returned to the mark without delay. A deliberate delay gives the other team a penalty ten metres forward of the mark.
• After an intercept, the first touch for the new attacking team is zero touch.
• Both attackers and defenders must use the minimum force necessary to make a touch and must not pose an unnecessary risk to player safety. The penalty is to the non-offending team at the point of the infringement.
• A defender may not claim a touch when no contact was made. The rule's listed ruling is a penalty to the attacking team and the offending player sent to the sin bin.
• A defender must not deliberately knock the ball from the hands of the player in possession during a touch. If the ball is accidentally knocked out during a touch, the touch counts and the attacking team keeps possession.
• A touch made on a player in possession while they are on or behind their own try line counts, and the rollball is seven metres forward of the contact point.

Source: FIT Playing Rules 5th Edition, definitions and rules 9 and 10.