How many planets can the naked eye see?

Or perhaps I should ask, which planets can be seen and which ones can’t? Obviously, maybe we can’t see some of the further ones. I’m aware that it’s possible to see some planets if conditions are right. Like Mars might appear as a reddish star, sometime in Spring. I really have no idea though. Maybe it’s different depending on where on Earth you are.
So out of our planets, how many can we see with the naked eye, and which ones? They probably all look like stars from far away, so the untrained eye might not know how to detect them.
I remember looking in a telescope some years back, and the owner said you could see Jupiter in it. He pointed out where, but there was just stars. Does the general populace even have strong telescopes like that at their disposal?
Inspired by Supermoon. I know absolutely nothing about space, stars and planets. so be gentle How can we even see planets anyways? They don’t have their own light source like a sun does. Or does a planet have to be in some specific position or whatever for it to be illuminated, thus allowing us to see them? So yeah, which ones can we see, how and why, and which ones can’t we see with the naked eye?