What are Concepts?

Concepts are mental icons that represent elements of another domain. The first domain may be in the physical world, in which case the mental icons represent entities of the physical world in mind space. Each situation of interest to humans is described by its own set of concepts. Classical mechanics is described in terms of particles, forces, and Newton's laws of motion. Chemistry uses the concepts of atoms, chemical kinetics, reactants, and products to describe chemical reactions.A concept is characterized by its properties, which may be intrinsic or extrinsic. Concepts may be further divided into fundamental and non-fundamental concepts. Fundamental concepts are those whose intrinsic properties are conserved.The concept of symmetry has an all-pervading influence on all spheres of our lives. A system has a particular symmetry if a transformation leaves a feature of the system invariant. The transformations occur in mathematical groups. The symmetry of a physical system may be linked to its conserved properties through Noether's theorem.