Need To Know:

No Higher: At 29,028' (8850m), about five miles up, the world's highest summit is at about the cruising altitude of a jet.

Local Names: in Nepal: Sagarmatha (means: churning stick in the sea of existence); in Tibet: Chomolungma (means: mother goddess of the universe). Once known to Westerners as Peak XV, Everest was named for Sir George Everest, the British surveyor-general of India, in 1859.

Thin Air: Decreasing atmospheric pressure at high altitude means there are less oxygen molecules in a given space. At the top of Mount Everest, the actual percentage of oxygen in the air is the same as that at sea level (about 20%). However, the atmospheric pressure at the summit of Everest is 33% that of sea level. So if you had a shoe box full of air, there would be 66% less oxygen in the box at the summit of Everest than at sea level. Each breath pulls in 33% of the oxygen as that at sea level.

The Death Zone: Above 26,000' there's about a third of the oxygen available at sea level. Even acclimated, the body begins to shut down, and if a person stays that high long enough, they will die. Most climbers use oxygen here for climbing and sleeping.

Because It's There: in 1924, George Mallory and Andrew Irvine, GBR, were last seen going strong for the top on the north side of the mountain. It is unknown if they reached the summit before disappearing. In 1921, Mallory had led the first ever expedition to Everest.

Wind: climber Dave Breashears has compared the ominous sound of evening winds on the upper mountain to that of a 747 jet taking off endlessly.

Narrow Window: weather on Everest permits reasonable climbing only in May and October between winter snows and summer monsoons.

First Ascent: 1953, Sir Edmund Hillary, NZ and Tenzing Norgay, Nepal, via the South Col Route. Neither has ever said who stepped on the summit first.

Fastest Ascent: October 17, 1998, Kagzi Sherpa of Nepal climbed Everest in 20 hours 24 minutes to break Frenchman Mark Batard's longstanding mountaineering record from October 1990 when Batard did it in 22 hours 29 minutes.

Most Summits: 10 summits by Ang Rita Sherpa of the Solukhumbu region of Nepal. On May 26, 1999, Apa Sherpa of Nepal reached the summit at 11am tying Ang Rita's record.

Longest Time Spent on the Summit: on May 7th, 1999, Babu Chirri Sherpa of Nepal set a new record by spending 21 hours on the summit without oxygen.

Youngest Summiter: Shambu Tamang of Nepal, 16 years old, reached the summit on May 5, 1975.

Oldest Summiter: Lev Sarkisov (12/2/38) of Georgia reached the summit on May 12, 1999. At 60 years and 161 days old, he beat Spaniard Ramon Blanco's record by one day.

First Oxygenless Ascent: 1978, Reinhold Messner, ITL, and Peter Habeler, AUT, via the South-East Ridge.

First Solo Ascent: 1980, Reinhold Messner, via the North Col to North Face.

First Ascent by a Woman: 1975, Junko Tabei, JAP, via the South-East Ridge.

First Ascent by an American: 1963, James Whittaker, via the South-East Ridge.

First Ascent by an American Woman: 1988, Stacy Allison, via the South-East Ridge.