In the mountaineering parlance of the Western United States, a fourteener is a mountain peak with an elevation of at least 14,000 ft (4267 m). The 96 fourteeners in the United States are all west of the Mississippi River. Colorado has the most (53) of any single state; Alaska is second with 29. Many peak baggers try to climb all fourteeners in the contiguous United States, one particular state, or another region.

Peak bagging or hill bagging is an activity in which hikers, climbers, and mountaineers attempt to reach a collection of summits, published in the form of a list. This activity has been popularized around the world, with lists such as 100 Peaks of Taiwan, four-thousand footers, 100 Famous Japanese Mountains, the Sacred Mountains of China, the Seven Summits, the Fourteeners of Colorado, and the eight-thousanders becoming the subject of mass public interest.