That is the Vertex
The intersection of a plane with a solid figure is the set of points where the plane cuts through the solid. This intersection can take various forms depending on the orientation and position of the plane relative to the solid; it can be a point, a line, or a two-dimensional shape (such as a circle or polygon). The specific nature of the intersection is determined by the geometry of both the plane and the solid figure involved.
A vertex is the point where three or more edges of a solid figure meet.
There is no solid figure with only four edges. The smallest solid figure is the tetrahedron, made up of four triangular faces, but it has six edges.
You have to count the lines on a solid figure
The point where three or more edges of a 3D figure meet is called a vertex. In geometric terms, a vertex is a fundamental component of polyhedra and other solid figures, serving as a corner or a junction point for the edges. Each vertex can be connected to other vertices by edges, forming the overall shape of the solid.
If you are a solid figure with no vertices or edges, then you are a Sphere.From the lighter side: And that means that we can no longer be friends...
sides of the solid figure
EDGES
Cube
hexahedron
CIRCLE
A vertex on a cube, for example, is where any three edges meet. On a pyramid (square type) it could be at the point on the top or the 4 bottom edges. :)