Short for Biological Diversity, the term is used to refer the variety of life on Earth and all of the natural processes; variety of different species (species diversity), genetic variability among individuals (genetic diversity), variety of ecosystems (ecological diversity) and variety of functions such as energy flow and matter cycling (functional diversity). 

It concerns the patterns of distribution of species over the face of the globe and understanding the origins and mechanisms which determine the distribution.

Any living factor that affects another organism; plants, animals, fungi, protist and bacteria are all biotic or living factors.

See habitat