1. A computer-implemented method comprising: providing, by one or more processors and to a user, a plurality of questions with known answers; receiving, at the one or more processors and from the user, answers to the plurality of questions with known answers; determining, by the one or more processors, a quantity of the answers that are correct answers; determining, by the one or more processors and based on the quantity of answers that are correct answers, that the user is human; providing, by the one or more processors, a first image to multiple users, the multiple users including the user; receiving, at the one or more processors and from the multiple users, terms identifying the first image; discarding, by the one or more processors, terms, of the received terms, that were received from users, of the multiple users, determined not to be human, the discarding forming a set of terms; identifying, by the one or more processors and from the set of terms, a first term and a second term as related terms; and associating, by the one or more processors, the first term as a label with the first image.