According to Salmond, Legislation is that source of law which consists in the declaration of legal rules by a competent authority. and legislation is used in three senses 1. For all forms of law making (wider sense) 2. For all expressions of the will of the legislative (strict sense) 3. For the creation of law by way of authoritative declaration (sub-ordinate)
Sir John Salmond refers to eight kinds of law, Imperative Law, Physical (Scientific) Law, Natural (Moral) Law, Conventional Law, Customary Law, Practical (Technical) Law, International Law and Civil Law. "Imperative Law means a rule of action imposed upon mere by some authority which enforces obedience to it."
Law is a social science grows and develops with the growth and development of society. New developments in society create new problems and law is required to deal with those problems. According dictionary definition of Law, it means a rule established by authority or by custom. It regulates the behaviors of a community, Country, etc.