[Musar refers books about Ethics from the Rishonim {medieval authors}and a few achronim [later authors]. Rishonim means people from the Middle Ages. The books of Achronim refers to a few books written about ethics after around 1520 or any time during or after Rav Joseph Karo. But the term {Musar} also got expanded to mean even the books of the disciples of Rav Israel Salanter. While I was at the Mir in NY, I made it a point to go through as much of that material as I could. (But not during the two official learning sessions which were for Gemara only. The Musar study I did on my own time.) The two books that affected me the most were the Or Israel by Rav Isaac Blazer and the Madragot HaAdam by Joseph Yozel Horwitz of Navardok. The first brings out the importance of Fear of God and good character traits. The second shows the importance of trust in God.]