The eight-thousanders are 14 mountains recognized by the International Mountaineering and Climbing Federation (UIAA) with summits that exceed 8,000 metres (26,247 ft) in elevation above sea level and are sufficiently independent of neighbouring peaks as measured by topographic prominence. There is no formally agreed-upon definition of prominence, however, and at times the UIAA has considered whether the list of 8,000-metre peaks should be expanded to 20 peaks by including the major satellite peaks of the canonical 14 eight-thousanders. All of the Earth's eight-thousanders are located in the Himalayan and Karakoram mountain ranges in Asia, and their summits lie in the altitude range known as the death zone, where atmospheric oxygen pressure is insufficient to sustain human life for extended periods of time.
From 1950 to 1964, all 14 of the eight-thousanders were first summited by expedition climbers in the summer season (the first to be summited was Annapurna I in 1950, and the last was Shishapangma in 1964); from 1980 to 2021, all 14 were summited in the winter season (the first to be summited in winter was Mount Everest in 1980, and the last was K2 in 2021). As measured by a variety of statistical techniques, the deadliest eight-thousander is Annapurna I, with one death (climber or climber support) for every three summiters, followed by K2 and Nanga Parbat (each with one death for every four to five summiters), and then Dhaulagiri and Kangchenjunga (each with one death for every six to seven summiters).
