What tenses to use at what time?

To master English perfectly and understand when to use the present, the past or the future, there are some rules.
Conjugation in English seems simpler than in Spanish, since there are fewer tenses and fewer conjugated forms to learn. However, it remains complex.

The  present simple  is used for three main reasons: What tenses to use at what time?

Describe a  habit, a repetition: He smokes every day.
A  state  or a general truth: The sky is blue.
An  official future action, which will inevitably happen: The plane leaves at 8pm tomorrow .
The  past simple  is used for two reasons:
A  past action, which already occurred at a specific time: I watched a movie yesterday.
A  past custom  unrelated to the present: I lived in Madrid before my moving to Barcelona .
This is complicated by the use of the  present continuous :
To designate an  action in progress : I am playing football in the park.
A  description  in the present: She is listening to music.
A  near future  with a notion of intention: I am leaving to the USA tomorrow.
The  past continuous  meets the same rules (except the future):
The  past action  that was happening: I was having a bath when someone rang the door.
A  description  in the past: She was wearing a blue scarf .
The  present perfect  is used to connect the past with the present: I have bought you something . Often used with ever / never, already / yet, it is the first time, for / since, and just .
The  present perfect continuous  is used to designate an action that started before the moment of speaking and has not finished yet: How long have you been waiting for him?
The  future is expressed in many ways:
With the modal  will for an instant decision, a prediction or to show your determination ( I will pass this exam ).
With  going to : to mark the intention or a prediction resulting from an observation ( Look at the sky: it is going to rain! ).
With the  present continuous  as we have already said.
With to be to express the will of others ( I am to pick up at 5am ).
With to be about to to express an immediate future: I’m about to cry ( I’m about to cry ).
If you can understand and use these forms without errors, you can move on to studying the conditional and subjunctive without worry!