What is alive?

Alive is a term used to describe something that is living and having the ability to carry out essential life functions such as respiration, metabolism, growth, reproduction, movement, and response to stimuli. Living things are composed of cells, the basic unit of life, which perform the critical functions for the organism, and are capable of adapting to changes in the environment. The term alive is used to differentiate between living organisms and nonliving things such as rocks, water, and soil.