When people say the word "convention," they are usually referring to large gatherings of the employees of companies and corporations who attend a mass assembly, usually in a big hotel somewhere, for the purpose of pretending to learn stuff when they are in fact enjoying a free trip somewhere, time off work, and the opportunity to flirt with strangers, drink, and otherwise indulge themselves. The first major difference between a business convention and a fan-dom convention is that fandom doesn’t bother with the pretenses. They’re just there to have a good time. The second difference is the dress code— the ensembles at a fan convention tend to be considerably more novel.