Before an A.I. system can learn, someone has to label the data supplied to it. Humans, for example, must pinpoint the polyps. The work is vital to the creation of artificial intelligence like self-driving cars, surveillance systems and automated health care.

Artificial intelligence is being taught by thousands of office workers around the world. It is not exactly futuristic work.

At iMerit offices in Kolkata, India, employees label images that are used to teach artificial intelligence systems. Credit Credit Rebecca Conway for The New York Times.