Real-Time Strategy (RTS for short) is a genre of martial-arts video games practiced in Real Time. This is not to be confused with the less popular (and widely considered inferior) Fake-Time Strategy games.
In ancient Japan (pre- 1987), in the days before video games, Real-Time Strategy was actually a form of martial arts. Those that practiced Real-Time Strategy actually had to fight each other in real life, causing many samurai to die at the hands of fellow practitioners (notable examples include Black Jesus, your mom, and This Guy, though in the case of Black Jesus it was AIDS that killed him... but thats another story completely unrelated to this). In order to keep warriors alive and able to defend Japan, Japanese leaders sought another way to amuse them, other than having them keep killing each other, that is. Thus in 1988 Real-Time Strategy as we know it was born.
Soon after the first Real-Time Strategy game was released in Japan, another game was released in the United States of Europe which claimed to be an RTS game. This game was widely adopted by the western world as RTS, while REAL RTS games (Street Fighter for example) were misidentified as "Fighting" games. Evidence of this can be seen with the Wikipedia article on Real-Time Strategy .
Why it's called Real Time Strategy
RTS starts with Real, because it is. If you die in the game, you die for real. These types of games have been around for years for use in schools where learning life skills is as easy as playing a game. Most of these real games have been used by karate and tie-bo masters for millennia to train.
Adoption by Oscar Wilde