The Tosafists - Ba'alei Tosafot - were members of a school of Torah and Talmudic interpretation which flourished in 12th and 13th century France and Germany. Their roots are in the work of Rashi – in fact Rashi's sons-in-law and grandsons are counted amongst the founders and most influential members of the school of Tosafot. Their comments on almost every tractate of the Talmud were collected, edited, augmented and passed on for generations, with certain collections gaining more prominence (depending on tractate and locale). Their approach is analytical, comparative and incisive, and many times takes a critical stance regarding Rashi's commentary. They were amongst the first French and German rabbis to quote extensively the Jerusalem Talmud and the Talmud commentary of Rabbenu Chananel (of North Africa). Other works also emerged from their school, most notably Machzor Vitri and the Torah commentary, Da'at Z'kenim.