We use the present simple tense when we speak about something permanent and regular. We may divide these cases into three groups.
1) Common knowledge
We use the present simple to talk about well-known facts, something that everyone knows.
The moon goes round the Earth.
The wolf is a wild animal.
2) More or less permanent situations, skills, preferences
When something is stable and doesn't change over a long period, we use the present simple.
I work in a bank.
We live in Paris.
She doesn't like olives.
I speak English and French.
3) Habits, regular actions
We all have our habits, good or bad, and things we do regularly. In this case, we use the present simple, too.
I meet my friends every Friday.
You always have tea for breakfast.
She never wears skirts and dresses.
We do not use the present simple tense if the action is happening right now, at the moment of speaking. Compare these examples.
I read a lot of books on psychology. but Now I'm reading a very interesting article.
I have a shower every morning. but Kate, answer the phone, please! I'm having a shower.