I assume that the reader is already familiar with "non-cooperative game theory". It's what everyone already knows, usually just by the name "game theory". The typical definition of "cooperative game theory" isn't very helpful for understanding the difference between the two, which is why I'm providing an example instead.

But here's Wikipedia's definition of "cooperative game":

A cooperative game is a game where groups of players ("coalitions") may enforce cooperative behaviour, hence the game is a competition between coalitions of players, rather than between individual players. An example is a coordination game, when players choose the strategies by a consensus decision-making process.