What does it mean to get an electric shock from touching someone, according to science?

You’re walking along, you reach out to someone… and bang! A small shock runs through your fingers. Surprising, sometimes slightly unpleasant, often misunderstood: this feeling that someone is « electrocuting » you is not uncommon. But then, what exactly is happening? And above all, is it dangerous? Rest assured: not at all. But it is very interesting.