Common law
The common lawso named because it was "common" to all the king's courts across Englandoriginated in the practices of the courts of the English kings in the centuries following the Norman Conquest in 1066. The British Empire spread the English legal system to its historical colonies, many of which retain the common law system today. These "common law systems" are legal systems that give great precedential weight to common law, and to the style of reasoning inherited from the English legal system.
Civil law (legal system)
Civil law takes as its major inspiration classical Roman law ("c". AD 1–250), and in particular Justinian law (6th century AD), and further expanded and developed in the late Middle Ages under the influence of canon law. The Justinian Code's doctrines provided a sophisticated model for contracts, rules of procedure, family law, wills, and a strong monarchical constitutional system. Roman law was received differently in different countries. In some it went into force wholesale by legislative act, i.e., it became positive law, whereas in others it was diffused into society by increasingly influential legal experts and scholars.