Equity is a system of law that supplements and complements the rules of common law, which is a system of law based on precedent and custom. In other words, equity is a separate body of law that is applied in addition to common law.

Equity is often administered by a separate court system, such as the Court of Chancery in England or the Court of Equity in some states in the United States. These courts have the authority to apply the principles of equity in cases where the rules of common law are not sufficient or where they would result in an unfair outcome.

Equity is based on the principles of fairness and justice, and it aims to provide remedies for situations where the common law does not provide a suitable solution. It is an important aspect of the legal system and is used to ensure that the law is fair and just, and that it is able to adapt to the changing needs of society.