What is a listing?

In discussing the home selling process, the following question comes up periodically. "What exactly does "listing the house" mean?  

To a real estate agent, this question seems like common sense.   Something that everyone knows, but surprisingly, the question comes up more often than would be expected.  

Listing Property:  History of the Term

The earliest known use of the word listing is said to come from members of a community placing their home on a list, usually at a general story or church, to let other members of the community know of their intention to sell the property.  Trips to the general store were more than what a modern consumer