Anasazi is a common term for Ancestral Puebloans, the ancestors of the modern Pueblo peoples. The term "Anasazi" is not preferred by their descendents, though there's no consensus amongst them on a native alternative. The word is Navajo for "Ancient Ones" or "Ancient Enemy."
The civilization is perhaps best-known for the jacal, adobe and sandstone dwellings that they built along cliff walls, particularly during the Pueblo II and Pueblo III eras. The best-preserved examples of those dwellings are in parks such as Chaco Culture National Historical Park, Mesa Verde National Park, and Canyon De Chelly National Monument. These villages, called pueblos by Mexican settlers, were often only accessible by rope or through rock climbing.
They also left behind a lot of petroglyphs and pictographs.
The Anasazi disappeared for as yet undetermined reasons. Many have speculated that a change in local climate and resulting agricultural failures may be the reason.