This verb tense is used to express an action that will take place in the future. It's generally reserved for something that will begin and end in the future. It's a statement of fact, made with certainty.
1) will+ verb (shall+ verb is also grammatically correct, but isn't as popular anymore)
"I will travel to Greece tomorrow," or, "I shall travel to Greece tomorrow."
2)to be + going to + verb. For example, "I am going to eat a sandwich in Greece tomorrow," or, "We are going to sit by the sea."