(Hebrew: “additions”), critical remarks and notes on selective passages of the Talmud that were written mostly by unknown Jewish scholars in Germany, in Italy, and especially in France during the 12th to 14th century. Experts are undecided whether tosafot were meant to be direct commentaries on the two elements that comprise the Talmud—the Mishna (the codification of Jewish oral law) and the Gemara (expositions of the Mishna)—or were intended to supplement the great French rabbinical scholar Rashi's systematic commentary on the text of the Babylonian Talmud.

The first tosafists (baʿale ha-tosafot) were Meir ben Samuel and Judah ben Nathan, two of Rashi's sons-in-law who lived in northern France. The most highly regarded tosafist, however, was Rabbenu Tam (Jacob ben Meir Tam), Rashi's grandson. All editions of the Babylonian Talmud (since its first printing in Venice, 1520–23) carry Rashi's commentaries on the inside margin of the page, with the tosafot located on the outside margin. This arrangement, however, is not followed in some modern editions in translation. Extensive learning is required to understand the subtleties discussed in all these commentaries.