Jurisprudence, also known as theory of law or philosophy of law, is the examination in a general perspective of what law is and what it ought to be. It investigates issues such as the definition of law; legal validity; legal norms and values; and the relationship between law and other fields of study, including economics, ethics, history, sociology, and political philosophy.

Modern jurisprudence began in the 18th century and was based on the first principles of natural law, civil law, and the law of nations. Contemporary philosophy of law addresses problems internal to law and legal systems and problems of law as a social institution that relates to the larger political and social context in which it exists. Jurisprudence can be divided into categories both by the type of question scholars seek to answer and by the theories of jurisprudence, or schools of thought, regarding how those questions are best answered:

The terms "philosophy of law" and "jurisprudence" are often used interchangeably, though jurisprudence sometimes encompasses forms of reasoning that fit into economics or sociology.

Whereas lawyers are interested in what the law is on a specific issue in a specific jurisdiction, analytical philosophers of law are interested in identifying the features of law shared across cultures, times, and places. Taken together, these foundational features of law offer the kind of universal definition philosophers are after. The general approach allows philosophers to ask questions about, for example, what separates law from morality, politics, or practical reason. While the field has traditionally focused on giving an account of law's nature, some scholars have begun to examine the nature of domains within law, e.g. tort law, contract law, or criminal law. These scholars focus on what makes certain domains of law distinctive and how one domain differs from another. A particularly fecund area of research has been the distinction between tort law and criminal law, which more generally bears on the difference between civil and criminal law.

In addition to analytic jurisprudence, legal philosophy is also concerned with normative theories of law. "Normative jurisprudence involves normative, evaluative, and otherwise prescriptive questions about the law."

The English word is derived from the Latin, iurisprudentia. Iuris is the genitive form of ius meaning law, and prudentia meaning prudence (also: discretion, foresight, forethought, circumspection). It refers to the exercise of good judgment, common sense, and caution, especially in the conduct of practical matters. The word first appeared in written English in 1628, at a time when the word prudence meant knowledge of, or skill in, a matter. It may have entered English via the French jurisprudence, which appeared earlier.

Ancient jurisprudence begins with various Dharmaśāstra texts of India. Dharmasutras of Āpastaṃba and Baudhāyana are examples.

In Ancient China, the Daoists, Confucians, and Legalists all had competing theories of jurisprudence.