In parliamentary systems and presidential systems of government, primary legislation and secondary legislation, the latter also called delegated legislation or subordinate legislation, are two forms of law, created respectively by the legislative and executive branches of government. Primary legislation generally consists of statutes, also known as 'acts', that set out broad outlines and principles, but delegate specific authority to an executive branch to make more specific laws under the aegis of the principal act. The executive branch can then issue secondary legislation (mainly via its regulatory agencies), creating legally enforceable regulations and the procedures for implementing them. 
In the United Kingdom, secondary legislation (also referred to as delegated legislation or subordinate legislation) is law made by an executive authority under powers delegated by an enactment of primary legislation, which grants the executive agency power to implement and administer the requirements of that primary legislation.
Forms of secondary legislation in the United Kingdom include:
In Canadian law, primary legislation (also called statute law) consists of acts of the Parliament of Canada and the legislatures of the provinces, and of Orders in Council made under the Royal Prerogative. Secondary legislation (also called regulation) includes laws made by federal or provincial Order in Council by virtue of an empowering statute previously made by the parliament or legislature.
In the United States, primary legislation is, at the federal level, an Act of Congress, and the statute that delegates authority is called an authorizing statute or delegation of rule making authority.
A law promulgated by the executive branch agency of the United States Government as the result of primary legislation is called a regulatory law, as legislation is used only to refer to acts of the legislative branch, never the executive or the judicial branches. The body of law that governs the agency's exercise of rule making and adjudication powers is called "administrative law," primarily the Administrative Procedure Act.
[Legislative power] is vested exclusively in Congress [and judicial power] in the “one supreme Court” and “such inferior Courts as the Congress may from time to time ordain and establish”.... Agencies make rules... and conduct adjudications... and have done so since the beginning of the Republic. These activities take “legislative” and “judicial” forms, but they are exercises of—indeed, under our constitutional structure they must be exercises of—the “executive Power.”
Civil law systems are almost universal in Europe, with the exceptions of England, Wales, Northern Ireland and the Republic of Ireland, as well as in Central and South America, much of Africa and Asia.
Each member state of the European Union (EU) has its own laws, and there is also overall EU law. The founding treaty, the 1957 Treaty of Rome, and all subsequent treaties, such as the Maastricht Treaty, Nice Treaty, and Lisbon Treaty, are the main primary legislation. The Treaty of Rome gives powers to make secondary legislation.
Member states must surrender some national jurisdiction powers to the European Union; these delegated powers are exercised by the Commission, Council and European Parliament acting in concert, having consulted the European Economic and Social Committee and the European Committee of the Regions. The powers are exercised via binding Regulations, Directives, Decisions, and non-binding Recommendations and Opinions.
The Commission may take executive action in pursuance of policy, and may even act quasi-judicially in matters of EU competition law, a power defined in Article 101 and Article 102 of the Treaty on the Functioning of the European Union. Privileged parties, such as Member States, EU Institutions, and those with specific standing, may initiate litigation. For example, the Commission may sue Member States for breaches of EU obligations, and Member States may sue Institutions or other Member States for breach of EU law.