Ok. So how 'high' is high-altitude?

Altitude is defined on the following scale:

• High 8,000 - 12,000 feet OR 2,438 - 3,658 meters
• Very High 12,000 - 18,000 feet OR 3,658 - 5,487 meters
• Extremely High 18,000+ feet  OR 5,500+ meters

Some interesting comparisons:

• Mt. Kilimanjaro is about 19,340 feet OR 5,895 meters. That makes it Extremely High.
• I have jumped from planes at 11,000 feet high
• Base Camp to Mt. Everest (SouthEast Ridge) is around 17,700 feet and Northeast Ridge is 16,990 feet.