What is Res judicata "a matter adjudicated" and is it binding and determinative in later litigation?

Res judicata ("a matter adjudicated") is the rule that a final judgment on the merits by a court of competent jurisdiction is binding and determinative of the rights of the parties or their privies in all later suits with respect to fundamental issues decided in the former suit (issue estoppel) and with respect to causes of action and defenses that were decided (cause of action estoppel) or could and ought to have been decided in the former suit, the rule from Henderson v. Henderson. (1843), 67 E.R. 313, 3 Hare 100.