What does High Relief coin mean?

A high relief coin will have the details of the coin raised up more than a normal relief coin. It generally takes a lot longer and costs more to strike a high relief coin than a normal relief coin. High relief coins generally look better because the details are a lot sharper and they are usually more valuable because since high relief coins take longer to strike, a high relief coin is usually modified to be a normal relief coin to increase the speed in which they can be struck.