A dollar is a type of currency . Many countries have named their money the dollar , so in an encyclopedia article it is important to say which country the dollar is from that is being talked about , for example , the United States dollar or the Canadian dollar . Existing dollar units today are the Bahamian dollar , the Barbados dollar , the Belize dollar , the Bermuda dollar , the Brunei dollar , the Canadian dollar , the East Caribbean dollar , the Guyanese dollar , the Hong Kong dollar , the New Taiwan dollar , the Singapore dollar , the Trinidad and Tobago dollar , and the United States dollar .