DEFINITION OF PRESENT TENSES IN ENGLISH GRAMMAR

PRESENT TENSE

1) Simple Present Tense-

Indicates an action that is generally true or habitual. That is, it took place in the past , continue to take place in the present, and will take place in the future. This tense is used to denote
-a habitual action- for instance, "He walk to school."
-general truths- for instance, "The sun rises in the east", "Honesty is the best policy."
-a future event that is part of a fixed timetable- for instance, "The match starts at 9 o' clock."
Note
a. The form of Simple Present Tense is- verb (infinitive without 'to' and agreeable with the subject)

2)  Present Perfect Tense-

Indicates an action that has been completed sometime before the present moment, with a result

that affects the present situation.
For example, "He has finished the work."
                         "He has slept."
Note
a. The form of Present Perfect Tense is- has/have + verb (past participle form or 3rd form of the verb)

3)  Present Continuous Tense-

Indicates an action that is taking place at the moment of speaking.
For example, "She is walking."
"I am studying."
Note
a. the form of Present Continuous Tense is- is/am/are + verb + ing

4) Present Perfect Continuous Tense-

Indicates an action that started in the past and is continuing at the present time. 
For example, "He has been sleeping for an hour."
Note
a. The form of Present Perfect Continuous Tense is- has/have + been + verb + ing

Read More : What is Future Tense?Get Examples and Practice Exercise