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, or civilian law, is a legal system originating in Europe, intellectualized within the framework of Roman law, the main feature of which is that its core principles are codified into a referable system which serves as the primary source of law. This can be contrasted with common law systems, the intellectual framework of which comes from judge-made decisional law, and gives precedential authority to prior court decisions, on the principle that it is unfair to treat similar facts differently on different occasions (doctrine of judicial precedent, or "stare decisis").