To prevent oil getting by the oil ring and compression past the others. Also, if they were in line, it would tend to make a groove in the cylinder wall.
The piston rings create a seal between the piston and the cylinder wall.
Gently, they break easily. They also make tools to R&R piston rings to avoid breaking the rings.
Stagger the gaps so they don't line up.
Oil rings Combustion rings Piston rod Piston rop cap
The piston rings are fitted round the piston to make a better gas-tight fit in the cylinder.
Running an engine with broken piston rings will cause damaging scoring in the piston chamber, and is not to be recommended.
It is a spring metal sleeve that goes over a piston to compress the rings so that the piston can be install in the motor. It tightens down on the piston, forcing the rings into the grooves in the piston then you tap it into the cylinder.
Worn piston rings, bad valve seals,
on the tip of the plug it means you have bad piston rings in that cylinder.
You must replace the piston rings. That means TIME FOR A REBUILD.
You don't. The only solution to damaged piston rings is to take the engine block out of the car and replace the rings.