Ramban

Klalim

1. The Ramban's writings are complex and carefully written, so one must assess each word with great meaning, as nothing is extra.
2. The goal of many of the Ramban's Sefarim is to defend - the Bahag from the Rambam and the Rif from the Raavad and Baal HaMaor.
3. Ramban first wrote his disagreements on the Sefer HaMitzvot and then his Sefer.
4. The Ramban did not have the Rambam's Introduction to Perush HaMishnayot available to him, as Hebrew translations of the Arabic work were not yet available in Spain, according to the Yad Malachi, who posits that had they been available, the Ramban would not have been as quick to argue. The Rashba did not have the Perush HaMishnah available at all either.
5. Rabbeinu Yonah was a cousin of the Ramban, and his daughter married Shlomo, the Ramban's son.
6. The Ramban's direct students and their own students include the Rashba, Ra'ah, and Sefer HaChinuch.
7. In addition to his Chiddushim on Shas and Milchemet Hashem on the Rif, the Ramban filled the void of Halachot Rav Alfasi on Nedarim and Bechorot by writing his own work in the same spirit as the Rif. The Rosh on those Masechtot, therefore, is quoting the Ramban, not the Rif.
8. In contrast to his usual style of defending other Rishonim, the Ramban remarkably composed his own Sefer Halacha, Torat Ha'Adam, which is not only the source for swaths of Simanim in Shulchan Aruch, particularly Hilchot Avelut, but is also the starting point of many discussions in those contexts in the works of the Rishonim.
9. Torat HaAdam was probably written after the Milchamot Hashem and before the commentary on Iyov.
10. Later in life, the Ramban became engrossed with Kabbalah, which became a major basis for his commentary on the Torah.

Further Reading

1. Later Rishonim IV: Catalonia, by Rabbi Aryeh Leibowitz
2. Later Rishonim V: Ramban’s Talmud Commentary, by Rabbi Aryeh Leibowitz