Regulation is a term that refers to the codes and rules issued by the government and its agencies. Regulations are not exactly law, but they are to be adapted and followed due to the power given to them by law.
Regulations are a set of rules prescribed by a party superior in rank, position, and authority. These rules must be followed by everyone who is under influence of the authority. For example, pharmaceutical companies in United States have to follow the regulations set by FDA (Food and Drug Administration)