There are several ways to talk about the future. In addition to the future simple, we sometimes use present tenses speaking about events in the future.
On Wednesday I am playing tennis with Amy.
A: What are you doing tomorrow? B: I'm taking the dog to the vet, then I'm meeting my friend Monica and we're going shopping.
- To be going to — for intentions; when there are signs that something is just about to happen
Helen and Paul are going to get married.
I'm not going to give up.
Look at those dark clouds! It's going to rain.
The train leaves at 7:43.
The course begins in September.