How do words/phrase become an autofill in the topics section of Fluther questions?

I am interested in learning more about how topics become part of this elite circle.

When you type “a” in the topics box, suggested topics (such as Apple, animals, art, alcohol, answers, America, advice, aging, audio, and apartment) appear.

Sometimes, these pre-designated topics are spelled wrong, randomly capitalized, or have a period after them, which makes me think they come from having been entered by Fluther users. However, there are a number of topics that I have entered multiple times that are not yet an autofill topic, so I doubt it is that they are topics that are simply entered a certain number of times. (Also, it seems unlikely that multiple Fluther users would enter a topic and all put a period after it, capitalize it, or spell it incorrectly).

I am completely baffled by how topics become an autofill topic. Fluther gods, please inform.