If (conjunction)

1. Introducing a conditional clause.
2. Supposing that.

Origin:

Old english gif, of germanic origin; related to dutch of and german ob.

Examples:

1. If you study hard, you'll pass the test.
2. If it rains, we'll stay inside.
3. I'll go to the party if I finish my work on time.
4. If it's not too much trouble, can you help me?
5. If I were you, I would take the job.