Everest is one of the world’s deadliest mountains – yet literally thousands of people are drawn to Nepal and Tibet to climb it each year. Since it was first discovered in 1856, more than 4,000 climbers have reached its summit and these days, with pay-to-climb professional outfits and high-tech equipment, more than 600 manage to make it to the top every year. After two seasons when avalanches prevented any ascents – in 2014 and 2015 – things are getting back to normal. And as Base Camp begins to fill with this year’s climbers, here’s the low-down on the highest mountain on Earth.