We use the present simple to talk about actions we see as long term or permanent. It is a very common and very important tense.
Here, we are talking about regular actions or events.

• They drive to the office every day.
• She doesn't come here very often.

Here, we are talking about facts.  

• Water freezes at 0° C or 32° F.
• The Thames flows through London.

Here, we are talking about future facts, usually found in a timetable or a chart.

• Christmas Day falls on a Monday this year.
• The plane leaves at 5.00 tomorrow morning.

Here, we are talking about our thoughts and feelings at the time of speaking. Although these feelings can be short-term, we use the present simple and not the present continuous.

• They don't ever agree with us.
• I think you are right.