What is "world's oldest profession"

Usage examples of "world's oldest profession".

As the Indians retreated to their happy hunting grounds and the well-worn paths turned to paved roads, the teepees gave way to apartment buildings, and the practitioners of the world's oldest profession claimed the plush-lined cubby holes as their own.

The world's oldest profession was at least eighty percent theater, he recalled from his wild and reckless youth.

I almost smiled at the realization that the world's oldest profession had not yet been invented.