A rebate is a reduction or refund of the cost of a product. Most rebates are "mail-in" where the customer writes to the company and shows proof of payment. the company in turn refunds all or a portion of the cost.
A model aeroplane is used for presentations and testing. Model planes are also used for fun. They are used model-plane clubs, aeroplane company headquarters and studios. (Bedroom, in my house)
The ancient Germanic tribes and the ancient Scandinavians used runes as an alphabet. Prior to that, they used runes for magic purposes, such as casting lots (divination) and spells of protection.