Holden is a 140 km wide crater situated within the Margaritifer Sinus quadrangle region of the planet Mars, located with the southern highlands. Like Gusev, it is notable for an outlet channel, Uzboi Vallis, that runs into it, and for many features that seem to have been created by flowing water. It's believed that Holden Crater was formed by an impact between the Noachian to Hesperian Epochs. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On Mars large craters are named after deceased scientists, writers and others who have contributed to the lore of Mars. Small creaters (less than 60km) are named after small towns and villages.