The future tense is a tense which correlates with time later than the time of speaking. While some languages like Spanish, French and Italian have a distinct future tense, English has no future tense at all. In English, we have many ways of talking about future time. All of these involve present-tense forms:

The train leaves at 6 o’clock.
The train is leaving at 6 o’clock.
The train is going to leave at 6 o’clock.
The train will leave at 6 o’clock.

All of these sentences express different views of a future point, but none of them is a future tense in the strict sense of the term.

Future perfect

A special verb form which shows that something which is in the future now will be in the past at some point in the future. In English, the future perfect is expressed by the structures will have and shall have.

For example, if I say ‘She will have returned by Monday‘, this means that she has not returned by now, but that she will return on or before Monday, so that on Monday I will be able to say ‘She has returned’.

I will have finished my essay by evening.
He will have left for home.