Contract law simple explanation

A contract is an agreement between two parties that outlines the terms of conditions of the agreement. A contract can be in writing or given verbally. In order for a contract to be lawful and enforcable, consideration must be given by both parties. A contract protects the parties in case of breach of contract.

Principle in physiology

In physiology, the all-or-none law is the principle that if a single nerve fibre is stimulated, it will always give a maximal response and produce an electrical impulse of a single amplitude.
If the intensity or duration of the stimulus is increased, the height of the impulse will remain the same.
The nerve fibre either gives a maximal response or none at all.