Antarctica is technically the largest desert in the world.
Why it is true
A desert is defined by its very low annual precipitation. The interior of Antarctica receives less than fifty millimetres of precipitation per year, making it the largest polar and planetary desert.
Source: Climate Records
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.