A countermarked coin, also known as a counterstamped coin, is a coin that has been marked after being minted, normally by punching an impression into the surface. Countermarking was commonly done in the past to indicate a coin as fit for circulation, to revalue it, or to use it as currency in another location. Also, in some instances, coins have been stamped to advertise a company or commemorate an event. Countermarked coins punched by a non-official agent, such as a merchant or salesman, are normally considered damaged and do not usually hold much value. However, officially stamped examples, such as the well-known "holey dollar" of New South Wales, are often sought after by collectors and typically have higher collectible values.