The desert is a harsh mistress… No wait, that was the moon. Anyway, deserts are harsh places. A desert is defined as anywhere that receives less than 250mm of rain a year, which means that technically parts of Antarctica are deserts. What we usually mean, though, is an area of rock and sand with very little water and even less life.
They say you can survive 3 weeks without food, 3 days without water and 3 minutes without air (so I guess the moon really is harsher than any desert on Earth!). This means water management is extremely important if you wish to travel in the desert. What life there is tends to congregate around oases, the rare water sources which do appear in many deserts, or it lies dormant until the rare rains. In the Atacama Desert, in Chile, there is a phenomenon called the Flowering Desert – generally the area receives less than 12mm of rain a year, making it one of the driest places on the planet but every so often it receives heavy rain and the seeds germinate – for a few days the entire region is covered in thousands of species of wild flowers, and teeming with life which takes advantage of them. It is said to be absolutely beautiful.
The other problem with deserts is temperature – everyone knows deserts are hot (well, except for Antarctica), but the temperature drops rapidly at night, often falling below freezing. Many a traveller has frozen to death because they were unaware of that.