The  Present Simple tense is the most basic tense in English and uses the base form of the verb (except for the verb be ). The only change from the base is the addition of s  for third person singular.

How do we make the Present Simple tense?

There are two basic structures for the Present Simple:

1. Positive sentences

subject+main verb
  Present Simple

2. Negative and question sentences

subject+auxiliary do+main verb
  conjugated in Present Simple  
do, doesbase

Look at these examples with the main verb like:

 subjectauxiliary verb main verb 
+I, you, we, they  likecoffee.
He, she, it  likescoffee.
-I, you, we, theydonotlikecoffee.
He, she, itdoesnotlikecoffee.
?DoI, you, we, they likecoffee?
Doeshe, she, it likecoffee?

From the above table, notice the following points...

For positive sentences:

  • There is no auxiliary verb.
  • We conjugate the main verb by adding s  to the third person singular.

For negative and question sentences:

  • The auxiliary verb (do) is conjugated in the Present Simple: do, does
  • The main verb is invariable in base form: base
  • For negative sentences, we insert not  between the auxiliary verb and the main verb.
  • For question sentences, we exchange  the subject and the auxiliary verb.
Emphatic do
Normally, for positive sentences we do not use the auxiliary verb do . But if we want to emphasize (stress) something, we may use it. For example, instead of saying "I like your dress", we could say "I do like your dress", just to show how much we like it. Here are some more examples:
  • I do wish you'd stop.
  • I do apologize.
  • You do look smart today.

Present Simple with main verb be

The structure of the Present Simple with the main verb be is:

subject+main verb be
  conjugated in Present Simple
am, are, is

Look at these examples with the main verb be:

 subjectmain verb be  
+Iam French.
You, we, theyare French.
He, she, itis French.
-Iamnotold.
You, we, theyarenotold.
He, she, itisnotold.
?AmI late?
Areyou, we, they late?
Ishe, she, it late?

From the above table, notice the following points...

  • There is no auxiliary verb, even for questions and negatives.
  • The main verb (be) is conjugated in the Present Simple: am, are, is
  • For negative sentences, we insert not  after the main verb.
  • For question sentences, we exchange  the subject and the main verb.

How do we use the Present Simple tense?

We use the Present Simple to talk about:

  • general time (action verbs)
  • situations now (stative verbs)
  • general time and situations now (verb be)

Present Simple for general time

We use the Present Simple tense when:

  • the action is general
  • the action happens all the time, or habitually, in the past, present and future
  • the action is not only happening now
  • the statement is always true
John drives  a taxi.
pastpresentfuture
 
It is John's job to drive a taxi. He does it every day. Past, present and future.

Look at these examples:

  • I live in New York.
  • The Moon goes round the Earth.
  • John drives a taxi.
  • He does not drive a bus.
  • We meet every Thursday.
  • We do not work at night.
  • Do you play football?

Present Simple for now

For stative verbs, we can use the Present Simple to talk about now . Stative verbs do not describe action. They describe state, and are verbs such as: like, sound, belong to, need, seem. We can use these verbs with the Present Simple tense to talk about a situation at the present time, not general.

I want  a coffee.
That sounds interesting.
Do you need  some help?
pastpresentfuture
 
 The situation is now. 

Present Simple for general time and now

The verb be  is always special. It is a stative verb, and we use it in the Present Simple tense to talk about now situations and about general  situations. Look at these examples of the verb be  in the Present Simple tense - some are general  and some are now:

I am  not fat.
Why are  you so beautiful?
Ram is tall.
pastpresentfuture
 
The situation is general. Past, present and future.
Am  I right?
Tara is  not at home.
We are hungry.
pastpresentfuture
 
 The situation is now. 

sources : Original Link