On May 15, 2012, Raymond Chen of Microsoft explained the term on his blog The Old New Thing. In a brainstorming session, people “designate a corner of the whiteboard to be the place to ‘park’ those ideas for later consideration.” “From what I can gather,” he wrote, that corner became the parking lot, and later the name passed to the document that collects the parked ideas.
An internal Microsoft presentation he quotes advises: “Avoid using Microsoft jargon terms, such as parking lot and dogfood.” Chen found no older source for the term.