Role playing games became popular with the Dungeons & Dragons™ (D&D) fantasy role playing game created and published by Dave Arneson and Gary Gygax of TSR in 1973.
It swept the gaming community by storm; particularly among young adults. Rights to the game were later obtained by Wizards of the Coast and Random House now owns the copyright.
D&D has since developed into Advanced Dungeons & Dragons™ (AD&D) as the rules were enhanced. Dozens of other companies have since published similar style games under a variety of titles, such as DragonQuest.™, RuneQuest™ and Tunnels and Trolls™.
As more players learned about role playing games, they branched out into other genres :-
Dungeons and Dragons™, which later became Advanced Dungeons and Dragons™ was the forerunner of the commercial role playing games. It is still the most popular.
Originally from TSR, it is now published by Wizards of the Coast.