Field recording is the term used for any recording produced outside of a recording studio. Field recordings can be either of two varieties. Field recording of natural sounds, also called Phonography (a term chosen to illustrate its similarities to photography), was originally employed as a documentary adjunct to research work in the field and foley work for film. With the availability of high-quality portable recording equipment, it has subsequently become an evocative art in itself. Both processed and natural phonographic recordings (such as the Environments series) are available.