Different Uses Of For

Purpose and cause

For can be used to talk about people’s purposes in doing something. It is then followed by a noun.

• I went to the college for an interview with Professor Mark.
• We stopped at the pub for a drink.

For + -ing form

For can be used before an -ing form to express the purpose of a thing especially when the thing is the subject of the clause.

• An altimeter is used for measuring height above sea level.

When the clause has a person as subject, it is more common to use an infinitive to express the purpose of a thing.

• We use altimeters to measure height above sea level.

For + -ing can also be used to explain the behaviour that causes a particular reaction.

• They punished the child for lying.
• We are grateful to you for helping us out.