When analyzing a composition, the point at which two parallel lines seemingly come together in the far distance of the horizon is referred to by professionals as the image’s vanishing point.
In your imagination, picture standing directly between two tracks on an abandoned railroad. If you were to look into the distance along the length of both tracks, at a certain point, they would appear to meet in the middle. This is the concept we’re referring to.
It’s also important to remember that any and all lines parallel to said railroad track lines will meet at that same vanishing point as well. For example, if there were a row of telephone lines running directly alongside the tracks, an imaginary line drawn through the tops of all the telephone poles would continue until it met the same vanishing points as the tracks it stood beside.