A desert is a place that has few, or sometimes even no, life forms. Sometimes life forms adapt to living in deserts, but conditions tend to be extreme, and survival is challenging. Some deserts can be visited but not lived in. Some deserts are so inhospitable that life as we know it cannot survive in them at all. In terms of rainfall, areas that receive less than ten inches of rain a year are considered to be deserts.
Some deserts receive only three or four inches of rain a year. A few places do not receive any rain at all. When we think about deserts, we think about limiting factors.
On earth, liquid water is necessary for life. Some life forms survive periods when water is not available by becoming spores or seeds, or by becoming dormant (hibernation). Some plants can survive for many years as seeds. Insects and unicellular life forms can also wait out drought. Sooner or later, however, liquid water is necessary. Survival is essential, but it is not all of life. Without growth and reproduction, life is on hold, not progressing.