Components of environments that an organism either exploits or must tolerate in order to survive and reproduce.

A niche includes what foods an organism can consume as well as physical attributes such as temperature or humidity (or indeed presence or absence of large amounts of liquid water), sunshine, seasonality (moisture or temperature extremes), whether there is sufficient shelter, etc. These are all things that an organism needs, is able to exploit within its environment, or otherwise must be able to tolerate.

Related to the idea of a niche is an organism's range, that is, what environments it is able to exist within, though the latter also is a function of whether an organism can successfully compete against other organisms found within the same environments. In fact, we can distinguished between an organism's fundamental and .html" title="Fundamental niche">realized niche, where the latter describes where an organism can exist given a lack of competition with other species whereas the latter describes where an organism can exist given such competition.