The Talmud has a famously distinctive page layout: the text itself resides in the center, and it is flanked by the medieval commentary of Rabbi Isaac ben Solomon (Rashi) on one side and that of his disciples (known as Tosafot) on the other, with various reference apparatuses in the margins, and then other commentaries in the outer margins. Introduced by Gentile printers of Judaica in 16th-century Italy, this format has been followed with minimal variation in almost every subsequent edition.
Yoel Finkelman delves into the origins of this format, and argues that its durability is rooted in unique features of Talmud study and pedagogy:
Rabbinic literature is layered. The entire discourse is dependent on this layered authority, in which earlier textual layers are formally more authoritative than later ones. Who is conceptually in an earlier layer than whom is central to understanding everything about how the Talmud serves as a grounding for later Jewish law. [The Talmud’s early stratum], the Mishnah, authored by tanna’im, is the foundational text, the bedrock. The Gemara, [the later stratum], is structured as a commentary on the Mishnah and is based on the principle that the post-mishnaic authorities, the amora’im, may not disagree with the earlier authorities. At most, amora’im can choose to agree with one tanna over another, . . . but structurally they do not argue with those who are in the layer above them on the hierarchy.
The same holds true regarding later commentators. Medieval rabbis don’t argue with the Gemara; they explain it. Both Rashi and Tosafot work with the assumption that the Talmud is the authoritative groundwork of their understanding. Their task is to explain it. . . . Placing Rashi and Tosafot on opposite sides visually matches the regular and consistent disagreements between the commentaries, both about specific readings and about their reading strategies and methods. Having these texts and commentaries on the same page allow not only for multiple texts and commentaries, but represent a dialogue that is occurring over real, chronological time and over conceptual, layered time.
Read more on Tradition: https://traditiononline.org/from-bomberg-to-the-beit-midrash-a-cultural-and-material-history-of-talmudic-page-layout/