Bonnie, please don't be confused by statements like Jon's that the "real" banjo is the tenor banjo. The fifth string was around long before the tenor banjo was invented. There's a painting from Thomas Jefferson's time of a slave playing a banjo that has a tuning peg partway up the neck for the thumbstring. Also, the Rijkmuseum vor Volkenkunde in the Netherlands has an old gourd banjo apparently made by a black slave in Suriname in around 1770. True, it had only four strings but one of those srings is a thumb string partway up the neck. Roscoe Sweeney, a white Virginian, is often credited with adding the fifth string, but the string he added was probably one of the full-length strings. When white people began playing the banjo, some of them had a hard time getting used to that thumb string. To make things easier, they invented banjos that had only four strings.