The Present Indefinite is used to denote future actions

1) In subordinate clauses of time, condition and concession after the conjunctions when, while, till, until, before, after, as soon as, as long as, once (time), if, unless, on condition (that), provided, in case (condition), even if, even though, no matter how, whenever, whatever, however (concession), etc.;

• We will start as soon as she is ready.

• Send for me, in case she feels worse.

• I'll have dinner whenever it is ready.

Note 1: In object clause after 'to see' (in the meaning of 'to understand'), 'to take care' and 'to make sure' the Present Indefinite is used to speak about future actions.

• I'll see that the lady is properly looked after.

• Her husband will make sure no harm comes to her.

• He will take care that no one interferes with them.

Note 2: The conjunctions 'if' and 'when' can introduce object clauses, then any future tense according to the sense is possible.

• I wonder if/when it will stop raining.

2) The Present Indefinite may be used to indicate a future action which is certain to take place according to a timetable, program, schedule, command or arrangement worked out for a person officially (a plan or arrangement regarded as unalterable). In this case the sentence usually contains an indication of the future time.

• We start for Istanbul tonight.

• His train arrives at 11.46.

• I start my new job tomorrow.

3) The use of the Present Indefinite with reference to the immediate future is structurally dependent in some special questions. In such questions one asks after the will of the person addressed. Thus the tense has a modal colouring.

• What do we do next?

• What do I say when I come in?

• Where do we go now?

4) In suggestions with Why don’t you...?

• Why don’t you take a day off tomorrow?

5) In descriptions of travel arrangements:

• On day three we visit Stratford-upon-Avon.

• We leave London at 10.00 next Tuesday and arrive in Paris at 13.00. We spend two hours in Paris and leave again at 15.00. We arrive in Rome at 19.30, spend four hours in Rome, etc.

The Present Indefinite is used to denote past actions:

1) In newspaper headlines, cartoons captions, chapter headings (perhaps because of its brevity and dramatic vividness):

• Peace Talks Fail

• Mass Murderer Escapes

2) In an informal style to describe a succession of past events (the historic present). Past events are portrayed or imagined as if they were going on at the present time, so we give the description greater reality. Mind that in such stories the present continuous is used for “background” – things that are already happening when the story starts, or that continue through the story.

• She arrives home full of life and spirit, and about a quarter of an hour later she sits down in a chair, gasps a bit and dies.

• There’s this Scotsman, you see, and he’s walking through the jungle when he meets a gorilla. And the gorilla’s eating a snake sandwich. So the Scotsman goes up to the gorilla...

• So I open the door, and I look out into the garden, and I see this man. He’s wearing pyjamas and a policeman’s helmet. “Hello,” he says...

3) The Present Indefinite is common in summaries of plays, stories, etc.

• In Act I, Hamlet sees the ghost of his father. The ghost tells him ....

• Chapter 2: Henry goes to Scotland and meets the Lock Ness Monster.

• May 1945: The war in Europe comes to an end.

4) More commonly, we report past events when using verbs of communication in the present to imply that what was said or heard still applies (often with the meaning of the Present Perfect) in the expressions I forget, I hear, I am told, I learn, I see, I understand. The Present Indefinite is used with a perfect or past meaning in introductory expressions like I hear, I see, I understand, I gather, etc.

• I hear you are getting married. (=I have heard)

• I am told she returned from France last week.

• I see there’s been trouble down at the factory.

• I hear you've come a long way.