With relevance to real-time strategy games, map control usually entails having access to multiple expansion sites, controlling a key choke point, or other such tactics that allow your units freedom of movement wherever they may need to go.

Having map control is advantageous because it allows you to expand all over the map and increase your resource intake, to pick and choose the location of your battles, and keeps your opponent from out-producing you. If performed correctly, you can use map control to force your opponent into a defensive position, and move in for the kill from there.