English Grammar – Tenses
Tense means time. The tense of a verb is the form or use indicating the time of an action or being.
Old English had only two tenses, – the present tense, which represented present and future time; and the past tense. We still use the present for the future in such expressions as, “I go away to-morrow;” “If he comes, tell him to wait.”
But English of the present day not only has a tense for each of the natural time divisions, – present, past, and future, – but has other tenses to correspond with those of highly inflected languages, such as Latin and Greek.
The distinct inflections are found only in the present and past tenses, however: the others are compounds of verbal forms with various helping verbs, called auxiliaries; such as be, have, shall, will.
Action or being may be represented as occurring in present, past, or future time, by means of the present, the past, and the future tense. It may also be represented as finished in present or past or future time by means of the present perfect, past perfect, and future perfect tenses.
Not only is this so: there are what are called definite forms of these tenses, showing more exactly the time of the action or being. These make the English speech even more exact than other languages, as will be shown later on, in the conjugations.
The English verb has never had full inflections for number and person, as the classical languages have.
When the older pronoun thou was in use, there was a form of the verb to correspond to it, or agree with it, as, “Thou walkest,” present; “Thou walkedst,” past; also, in the third person singular, a form ending in -eth, as in, “It is not in man that walketh, to direct his steps.”
But in ordinary English of the present day there is practically only one ending for person and number. This is the third person, singular number; as in, “He walks;” and this only in the present tense indicative. This is important in questions of agreement when we come to syntax.
Further reading: http://www.englishpage.com/verbpage/verbtenseintro.html