GOING TO - FUTURE FOR PLANS AND PREDICTIONS.

Going to is used to show a future intention.
-I'm going to go on holiday next summer.
- We're going to start our own business.
Form.
Going to future sentences are made as follows:
Subject - verb "to be" - going to - infinitive verb.
Example: They are going to have dinner.
Usage
Going to is used for future plans (=premeditated intention;not a decision now)
-I'm going to see my friends this evening.
- He's going to write a book.
- What are you going to do next summer?
-Are they going to study chemical engineering?

Going to is also used to make a prediction based on present evidence.
-He's going to fall over! (I can see he's in danger now.)
- She's going to win. (I can see she's winning now.)*********************************************
Compare.
Will and going to are both used for predictions and sometimes there is little difference in meaning.
-It will be sunny this afternoon. (A general prediction;my personal opinion about the future)
- It's going to be sunny this afternoon. (because it's getting warmer now)

Do an exercise: http://www.1-language.com/englishcoursenew/unit30_grammar_exs.htm

ADAPTED FROM: http://www.1-language.com/englishcoursenew/unit30_grammar.htm