The doctrine of res judicata consists of two different aspects. (Vezina v. Continental Cas. Co. (1977) 66 Cal. App. 3d 665, 669 136 Cal. Rptr. 198.) First, " ' "it 'precludes parties or their privies from relitigating a cause of action that has been finally determined by a court of competent jurisdiction.' " ' " (Ibid., italics added.) This aspect of res judicata has traditionally been referred to as "res judicata" or "claim preclusion." Second, " ''Any issue necessarily decided in such litigation is conclusively determined as to the parties or their privies if it is involved in a subsequent lawsuit as to the parties on a different cause of action." (Id. at pp. 669-670.) This latter aspect of res judicata is known as "collateral estoppel" (ibid.) or "issue preclusion." (Vandenberg v. Superior Court (1999) 21 Cal. 4th 815, 824 88 Cal. Rptr. 2d 366, 982 P.2d 229; Kelly v. Vons Companies, Inc. (1998) 67 Cal. App. 4th 1329, 1335 79 Cal. Rptr. 2d 763.) Res judicata is applicable only to the same causes of action between the same parties or their privies. As stated in Branson v. Sun-Diamond Growers (1994) 24 Cal. App. 4th 327, 340 29 Cal. Rptr. 2d 314: 'In its primary aspect, res judicata operates as a bar to the maintenance of a second suit between the same parties or parties in privity with them on the same cause of action.' (See also Krier v. Krier (1946) 28 Cal. 2d 841, 843 172 P.2d 681 "It is settled, however, that a judgment in a prior action between the same parties on the identical cause of action is res judicata, and a bar to a second suit thereon . . . ."; Goddard v. Security Title Ins. & Guar. Co. (1939) 14 Cal. 2d 47, 51 92 P.2d 804 "First, a final judgment, rendered upon the merits by a court having jurisdiction of the cause, is conclusive of the rights of the parties and those in privity with them, and is a complete bar to a new suit between them on the same cause of action. This is the general doctrine of res judicata'.) Since a retraxit "invokes the principles of res judicata," it of course follows that a retraxit only bars claims dismissed with prejudice between the same parties or their privies. (Datta v. Staab (1959) 173 Cal. App. 2d 613, 621 343 P.2d 977 " 'A retraxit is equivalent to a verdict and judgment on the merits of the case and is deemed to be a bar to another suit for the same cause between the same parties. . . .' " (Italics added.); Torrey Pines Bank v. Superior Court, supra, 216 Cal. App. 3d at p. 820 "A retraxit is equivalent to a judgment on the merits and as such bars further litigation on the same subject matter between the parties." (Italics added.); Moradi-Shalal v. Fireman's Fund Ins. Companies (1988) 46 Cal. 3d 287, 312 250 Cal. Rptr. 116, 758 P.2d 58 " 'Where the parties to an action settle their dispute and agree to a dismissal, it is a retraxit and amounts to a decision on the merits and as such is a bar to further litigation on the same subject matter between the parties'.) Since res judicata bars a subsequent action on the same claim between, not only parties to the first action, but also their privies, we must determine who qualifies as a privy to a prior action. In Bernhard v. Bank of America (1942) 19 Cal. 2d 807 122 P.2d 892, Justice Traynor stated: "Under the requirement of privity, only parties to the former judgment or their privies may take advantage of or be bound by it. A party in this connection is one who is 'directly interested in the subject matter, and had a right to make defense, or to control the proceeding, and to appeal from the judgment.' A privy is one who, after rendition of the judgment, has acquired an interest in the subject matter affected by the judgment through or under one of the parties, as by inheritance, succession, or purchase." (Id. at p. 811.)