Learning Tenses - Step Eight - Future Perfect

• This has both simple and continuous forms, and refers to time which we look back at from a future point

Examples: In the 2 years time I'll have finished the book.
By the end of the month, I'll have been working for this firm for a year.

• It can also be used to express an assumption on the part of the speaker.

Example: You won't have heard the news, of course.



http://www.englishpage.com/verbpage/futureperfect.html