A. There’s a cycle of tractates, usually an eight-year rotation. Most Yeshivas study the 3 Bavas: Bava Kamma (damages) Bava Metziah (monetary disputes & doubts) and Bava Basra (real-estate, property disputes, zoning and inheritance). Also commonly learned are marital tractates (mostly for the extensive discussion on documents and contracts) titled: Kesubos, Kiddushin and Gittin. Chabad Yeshivas also include Shabbos (Shabbat) and Pesachim (Passover) because the Rebbe wanted that the variety include topics relevant in everyday Jewish living. The Brisk Yeshiva makes a point of learning tractates of Temple Laws such as Zevachim and Menachos to prepare for Moshiach. Of course there are many more tractates but they are not usually studied in the official cycle. Yeshiva students can opt to study them on their own, in a Daf-Yomi cycle, or during summer months with lighter curriculum.
