In any case, Euclid became the founder of the book (the so-called "Euclid geometry"), but the faces mentioned in the book do not refer specifically to planes, and lines are not limited to straight lines. Therefore, euclid's line is also thought to contain a curve of one side (edge) that appears when the surface is cut
Curves appear in two-dimensional space (planar or surface) or three-dimensional space (stereo). However, curves are still one-dimensional things. The reason for this is that the points on the curve can only be expressed by the amount (value) of distance.
We can see the edges of faces, or lines, all over the world. As I said just now, the one-dimensional line drawn on the paper must have a width, so the statement of calling it a line is not strict. The edge of the object opposite, that is, the boundary line between the object and another object (gas is also OK) without width, is the real one-dimensional line.