What is "pesachim"

Pesachim , often spelt Pesaḥim in academic writings, is the third tractate of Seder Moed ("Order of Festivals") of the Mishnah and of the Talmud. It is concerned mainly with the laws of the Jewish holiday Passover as well as the Passover lamb offering. The first four chapters cover the laws of chametz, chapters 5-9 discuss the laws of the Passover lamb offering, and the tenth and final chapter discusses the order of the Passover seder, as well as the law of pairs.