The last website I chose talks about what perspective is. I also provided a video to support what it says. In the website, it says that perspective has different ways it presents itself, as it has one to three vanishing points. when you do perspective, it used math called projective geometry.
The video i got talks about how in 3D sidewalk paintings, if you look right above, it will look extremely distorted, but from the side however, it looks like it is popping up. this all works because it uses mathematical techniques old artists used back then, and what we still use today.