A complete Self Study Tenses with Senses

ACCORDING TO BRITISH AND AMERICAN GRAMMAR

• PAST
• PRESENT
• FUTURE 

Tense: Any of the forms of a verb that may be used to show the time of the action or state expressed by the verb.
(Oxford Advanced learner's Dictionary)

Tense: Any of the forms of a verb which show the time at which an action happened.
(Cambridge Advanced learner's Dictionary)

Tense is a grammatical category that is realized by verb inflection. Since English has no future inflected form of the verb, that threefold semantic opposition is reduced to two tenses: the Present tense and the Past tense, which typically refer to Present and Past time respectively. (A Student's Grammar of the English language by Greenbaum &Quirk)