Or the About page on soundtransit.nl:

2) What is Phonography?

Phonography is the art of recording sounds from the environment around us, with an emphasis on the unintentional sounds which often go unnoticed in our daily lives. An international community of phonographers collect and share their recordings, with interests ranging from recordings of natural or urban environments to improvised situations or “soundwalks” to the resonance of solid objects or the Earth’s atmosphere. The Phonography community gets together largely through a website, a Yahoo group and via recordings on various labels such as Seattle’s and/OAR records.