Sure, psi pound per square inch is a unit of pressure. It stands for pound-force per square inch. It is a unit used to measure pressure, which is the force exerted on a surface per unit area.

The psi unit is equivalent to:

• 1 psi = 1 pound-force per square inch = 68.94 Pascals

Therefore, psi is a unit of pressure that is commonly used in the United States, but it is also used in other countries as well.