How does Parachute works?

How does a parachute help a paratrooper land safely  ? 

  

A paratrooper with a parachute

When a paratrooper jumps from an air craft  and opens the parachute in the air, the surface area of the parachute increases and so  does the air resistance acting on the parachute.  Due to  more air resistance on the parachute,the acceleration of the paratrooper along with the parachute decreases and so does the velocity of the paratroopers and the paratrooper can land safely on the earth's surface without any injury.