A diploma mill refers to an institution that basically provides false diplomas to individuals who purchase them without having done the work to earn them. They may provide diplomas that look like the real deal to make someone look like they have certain credentials that they really have not taken the time to earn. It is illegal to run a diploma mill. Unfortunately, there are a lot of people who buy them before applying for certain positions simply because they want a certain type of job. Honesty is the best policy!