They have not size. Just a position.
The geometric term for the tip of a pen is a "point." In geometry, a point is a location in space that has no size or dimensions, represented by a dot. It is the most fundamental element in geometry and serves as the building block for all geometric shapes and figures.
The most basic building block of all geometric figures is simply the point. A point has no size or dimension but it does have a location. Lines are made up of a series of points.
naming a point
A point is surrounded by 360 degrees.
A line.
That would be the point.
Geometric points are dimensionless.
Point
Point
point
A point
A point