So what do you do if you have billions of images to label?

Employ tens of thousands of people?

Or create a game and get the world to do it for free. Quite brilliant. Not the game, the thinking.

The game is quite compulsive too. You are given a partner across the internet and have to bang as many one word descriptions of each image put in front of you as possible. When you match with your partner, you get points and move on. Frustrating if your partner is a dimwit or a rheumatic typist; strangely rewarding if you get someone on the same wavelength. My best score was 1100 in the allotted 90 seconds.