Verb Tenses: Simple Present

(See also Verbs -'Regular verbs in the simple present')

Note:

he, she, it: in the third person singular the verb always ends in -s:
he wants, she needs, he gives, she thinks.
Negative and question forms use DOES (=the third person of the auxiliary'DO') + the infinitive of the verb.
He wants. Does he want? He does not want.
Verbs ending in -y : the third person changes the -y to -ies:
fly flies, cry cries

Exception: if there is a vowel before the -y:
play plays, pray prays
Add -es to verbs ending in:-ss, -x, -sh, -ch:
he passes, she catches, he fixes, it pushes

See also Verbs -'Regular verbs in the simple present', and 'Be, do & have'

1. Third person singular with s or -es

to express habits, general truths, repeated actions or unchanging situations, emotions and wishes:
I smoke (habit); I work in London (unchanging situation); London is a large city (general truth)
to give instructions or directions:
You walk for two hundred metres, then you turn left.
to express fixed arrangements, present or future:
Your exam starts at 09.00
to express future time, after some conjunctions: after, when, before, as soon as, until:
He'll give it to you when you come next Saturday.

BE CAREFUL! The simple present is not used to express actions happening now. See Present Continuous.

For habits
He drinks tea at breakfast.
She only eats fish.
They watch television regularly.
For repeated actions or events
We catch the bus every morning.
It rains every afternoon in the hot season.
They drive to Monaco every summer.
For general truths
Water freezes at zero degrees.
The Earth revolves around the Sun.
Her mother is Peruvian.
For instructions or directions
Open the packet and pour the contents into hot water.
You take the No.6 bus to Watney and then the No.10 to Bedford.
For fixed arrangements
His mother arrives tomorrow.
Our holiday starts on the 26th March
With future constructions
She'll see you before she leaves.
We'll give it to her when she arrives.