A more thorough explanation:

Anglo-American common law is a body of law that comes from judicial decisions, rather than from statutes or constitutions. It is based on the English legal system and is used in many countries, including the United States.

For example, federal common law is the body of decisional law derived from federal courts when adjudicating federal questions and other matters of federal concern, such as disputes between the states and foreign relations, but excluding all cases governed by state law. Another example is American common law, which is the body of English law that was adopted as the law of the American colonies and supplemented with local enactments and judgments.

Common law is different from civil law, which is based on a written legal code. Common law is made by judges who decide cases based on morality, custom, and previous court decisions. Civil law is made by legislators who write laws and codes.

Overall, common law is a system of legal concepts and techniques that form the basis of the law in jurisdictions where the system applies. It is a general law common to the country as a whole, as opposed to special law that has only local application.