Charles de Gaulle International Airport has three terminals. Terminal 2 was built for Air France, but now hosts other airlines as well. The third terminal (T3, formerly T9) hosts charter and low cost airlines, such as easyJet.
The so-called "terminal 2" is actually not really a terminal, but rather a name applied to six distinct so-called "halls", which each possess a letter (from A to G). In other airports, such as JFK or LAX, these "halls" would simply be called terminals, so that Charles de Gaulle International Airport can be more properly described as having nine terminals altogether. When landing at or taking off from Charles de Gaulle International Airport, one should always know precisely which of the nine terminals/halls the plane lands or takes off from, as these can be located quite far apart from each other.
The nine terminals/halls are indicated distinctly on plane tickets: 1, 2A, 2B, 2C, 2D, 2E, 2F, 2G, 3.