Once upon a time, in the dark age of anime fans, there were no DVD's that had dual language for sale and very few companies sold the Japanese version on VHS. Thus fansubs were born. People would either buy or tape Dragon Ball off TV, take it home, translate and subtitle it themselves, then sell it on the black market. IE: Comic book shops and flee markets. And just so you know, yes it was illegal. They're now obsolete because of Japanese dubbing companies becoming aware that they can also make a profit off of the original Japanese product and because it's now easy to just add the audio track to a DVD.