1. PRIOR PLAN The decision was made before the moment of speaking
1.1. I am going to the beach next weekend with my friends
2. TIME EXPRESSIONS Tomorrow/tonight/soon/next month/this week/ in an hour
2.1. EXAMPLES
2.1.1. He is going to play soccer in an hour
2.1.2. You are going to go to the library tomorrow
2.1.3. I am going to play guitar the next weekend
3. GRAMMAR
3.1. Three different forms
3.1.1. AFFIRMATIVE
3.1.1.1. Subject + to be + going to + verb + complement
3.1.1.1.1. EXAMPLES
3.1.2. NEGATIVE
3.1.2.1. Subject + to be + not + going to + verb + complement
3.1.2.1.1. EXAMPLES
3.1.3. QUESTION
3.1.3.1. To be + subject + going to + verb + ...?
3.1.3.1.1. EXAMPLES
4. FUNCTION
4.1. Future plans and intentions
4.1.1. EXAMPLES
4.1.1.1. I have won $1,000. I am going to buy a new TV.
4.1.1.2. We're not going to see my mother tomorrow.
4.1.1.3. When are you going to go on holiday?
4.2. Predictions
4.2.1. EXAMPLES
4.2.1.1. The sky is very black. It is going to snow.
4.2.1.2. It's 8.30! You're going to miss the train!
4.2.1.3. I crashed the company car. My boss isn't going to be very happy!