The Fifty-Dollar Bill is a denomination of United States currency that features a portrait of Ulysses S. Grant, the 18th President of the United States. It is primarily used for transactions and is part of the series of notes issued by the U.S. Department of the Treasury. The bill is green in color, which is why U.S. currency is often referred to as "greenbacks." It has various security features, including a security thread and a watermark, to prevent counterfeiting. The Fifty-Dollar Bill is commonly used in everyday transactions and is also collected by numismatists.