Satellites or meteors? What are those lights in the sky and how to recognize them

How many times does it happen to look up, in a carefree evening with friends, and see strange and unexpected lights in the sky. They stand there, bright, moving slowly and then disappearing. Or they run fast in the sky and disappear in an instant. We take into consideration all the hypotheses that come to our mind, but in the end all that remains is to go to sleep full of doubts about what we have seen. Here are some of the most common answers to the question “what are those lights in the sky?”.