Tense, in grammar, is a term that expresses time in relation to the moment of action. Tenses are mainly indicated by changing the use of specific forms of verbs. For example, the verb ‘to be’ can become ‘am, is’ or ‘are’ in the Present Tense and ‘was’ and ‘were’ in the Past Tense. In case of Future Tense, the change is indicated by adding ‘shall’ or ‘will’ before the verb and they are formed by adding helping words or auxiliary words, like ‘be’ and ‘have’ before the relative verb.
The main purpose of a verb is to indicate the time of action. Hence, it is necessary to use the correct word or phrase which shows the time of the action, because sometimes the tense is not enough to explain the time of happenings. To solve the problem, a Past simple tense has words or phrases like 'yesterday / day before yesterday’, 'last week/month/year', 'a month ago' etc. The same is true for the Present simple and the Future simple.
There are three main verb tenses: present, past, and future. Each main tense is again divided into four parts, namely, Simple (or Indefinite), Continuous, Perfect and Perfect Continuous.
The use of some verbs in the Present, Past and Future Tenses are shown below:
Have – Today, I have to go out in the evening. (Present Simple) / Yesterday, I had to go out in the evening. (Past Simple) / Tomorrow, I shall have to go out in the evening. (Future Simple).
Like – I like the film. (Present Simple) / I liked the film. (Past Simple) / She will like the film. (Future Simple)
Cook – I cook my dinner. (Present Simple) / Yesterday, in the evening, I cooked my dinner. (Past Simple) / Tomorrow, I shall have to cook my dinner. (Future Simple)
Walk – Samir walks quickly. (Present Simple) / Yesterday Samir walked three miles at a stretch. / I shall walk tomorrow in the morning. (Future Simple).
It should be kept in mind that, in the Present Simple Tense, an ‘s’ or ‘es’ should always be added to the verb, in case of third person singular number. Examples – I like / She likes, You go/ Surya goes.