Definition :  The Future Perfect verb tense is used to compare an action or a point in time in the future with an action that happened before that future time.

Example:       I will eventually obtain my high school diploma.  To obtain my diploma, I must succeed a number of compulsory subjects.  It is thus impossible to get my diploma without my succeeding these subjects.  I can therefore express this with the following sentence:

            By the time I obtain my diploma, I will have succeeded all my compulsory subjects.

Note: It is necessary and obligatory to succeed in the subjects before obtaining the diploma.

How to write the Future Perfect:

To write the Future Perfect you must conjugate the future of the verb To Have with the Past Participle of the verb you are conjugating.