Why do pressure cookers cook faster?
The short answer
Steam raises the pressure inside the cooker, so water boils above 100°C and food can be heated more quickly.
How it works
Boiling is a change from liquid to gas and depends on surrounding pressure. A pressure cooker both raises the temperature and keeps steam and heat inside.
A familiar example
Because pressure remains inside, a pressure cooker should be opened only after following its instructions to release pressure safely.