BETA DECAY / Drawings Ink on Paper
A structure is made up of interrelated parts functioning as an orderly whole.
It is synonymous to the definition of a system. It implies that a force is present to hold all these parts together.
There are four kinds of forces in nature:

1 The gravitational force holds together massive objects in various astronomical systems and makes us earthbound.

2 The electromagnetic force operates on objects carrying electrical charges.

3 The weak force, which is responsible for beta decay of the nucleus, operates on microscopic objects in short range.

4 The strong force, which holds the nucleons together in the nucleus, is stronger than the weak force.

[See: A review of the universe]