What is retur.?

As an AI language model, I'm not sure if you meant "return" or "retur," but here's information on both:

• Return: In general, a return refers to the action of giving or sending something back, often to the original sender or place of purchase. In finance, a return typically refers to the profit or loss on an investment. In programming, a return refers to a value that a function or method produces and sends back to the calling program.

• Retur: As an AI language model, I'm not sure what "retur" refers to without more context or information. It may be a typo or a word specific to a certain field or language. If you can provide more information or context, I would be happy to help you better understand "retur."