Endeavour is an impact crater located in the Meridiani Planum extraterrestrial plain within the Margaritifer Sinus quadrangle region of the planet Mars. Endeavour is about 22 kilometers in diameter. Using Mars Reconnaissance Orbiter data, phyllosilicate-bearing outcrops have been detected along the rim of this crater. These minerals may have formed under wet conditions in a low-acidic environment during the early history of Mars. (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.