A flat surface that is infinitely large and with zero thickness
Clearly, when you read the above definition, such a thing cannot possibly really exist.
Imagine a flat sheet of metal. Now make it infinitely large in both directions. This means that no matter how far you go, you never reach its edges.
Now imagine that it is so thin that it actually has no thickness at all.
In spite of this, it remains completely rigid and flat. This is the 'plane' in geometry.
It fits into a scheme that starts with a point, which has no dimensions and goes up through solids which have three dimensions:
Planes are usually named with a single upper case (capital) letter in a cursive script such as
In another branch of mathematics called coordinate geometry, points are located on the plane using their
coordinates - two numbers that show where the point is positioned. To achieve this, the plane
is thought to have two scales at right angles. Using a pair of numbers, any point on the plane can be uniquely described.