We can use the present continuous, be + present participle, to talk about the future when we have already arranged to do something.

We can use be + going + to-infinitive to talk about something that we have decided to do in the future, but not arranged yet.

http://www.bbc.co.uk/learningenglish/english/course/lower-intermediate/unit-9/session-2/activity-3

Using the present to talk about the past.

http://www.bbc.co.uk/learningenglish/english/course/towards-advanced/unit-3/session-1

The present perfect is used for life experiences, recent past actions that are important now, past situations that are still happening now, and answering 'How long' questions usually with for or since.

The past simple is used for completed actions in the past.

http://www.bbc.co.uk/learningenglish/english/course/lower-intermediate/unit-26/session-2/activity-3

The present perfect continuous, have + been + present participle, is used to describe an activity that started in the past and is continuing now or has recently finished.

http://www.bbc.co.uk/learningenglish/english/course/intermediate/unit-2/session-2/activity-3

• ever: at any time in someone's life.
• never: not at any time in someone's life.

http://www.bbc.co.uk/learningenglish/english/course/lower-intermediate/unit-11/session-2/activity-5

The present perfect is often used with

• for meaning throughout a period of time or
• since meaning from a point in time to now

to talk about situations that started in the past and are continuing now.

http://www.bbc.co.uk/learningenglish/english/course/lower-intermediate/unit-12/session-2/activity-4

The present perfect is often used with

• just for something that happened only a short time ago,
• already when an action has happened before now or before we expected it to happen, and
• yet to ask if something has happened before now or to say something has not happened up to now.

http://www.bbc.co.uk/learningenglish/english/course/lower-intermediate/unit-14/session-2/activity-3

The present simple is used to describe things that we do regularly, facts, habits, truths and permanent situations.

The present continuous, be + present participle, is used to describe things that are happening at the time we are speaking, temporary situations and activities that are in progress. Stative verbs are not usually used in the present continuous.

http://www.bbc.co.uk/learningenglish/english/course/lower-intermediate/unit-2/session-2/activity-3

We use the present simple tense for things that we do regularly and for facts, habits, truths and permanent situations.

We use the present continuous for things that are happening at the time we are speaking, for temporary situations, and for activities that are in progress.

We use the present perfect for life experiences in the past, recent past actions that are important now, and past situations that are still happening now, often with how long, for and since; with just, already, yet for recent events.

http://www.bbc.co.uk/learningenglish/english/course/intermediate/unit-1/session-2/activity-3

We use the present simple for things that we do regularly and for permanent situations.

We use the present continuous for things that are happening now and for temporary situations.

We use the past simple tense when an action or situation happens and finishes in the past.

We use the present perfect to talk about our experiences in the past often with ever or never; to talk about situations that started in the past and are continuing now often with how long, for or since; to say whether an action has happened or not at the present time with just, already or yet.

We use the present continuous to talk about the future when we have made an arrangement to do something.

We use be going to + infinitive for future plans.

http://www.bbc.co.uk/learningenglish/english/course/lower-intermediate/unit-20/session-2/activity-3

Present verb forms can be used to talk about past actions.