Nashim ("Women" or "Wives") is the third order of the Mishnah (also of the Tosefta and Talmud), containing the laws related to women and family life. Of the six orders of the Mishna, it is the second shortest. The order consists of 7 tractates:
The traditional reasoning for the order of tractes (according to Rambam) is as follows. Yevamot is first because unlike the others, it is largely concerned with a compulsory commandment (levirate marriage) as opposed to a voluntary one. Ketubot follows as it signifies the beginning of married life. Nedarim follows because once a man is married to a woman, he has the legal right (under certain conditions) to annul her vows. Nazir, dealing with a special type of vow is a continuation on the subject of vows. The final section deals with the end of a marriage with Sotah which is concerned with infidelity and Gittin which is about actual divorce (Rambam's order swaps these two). Finally, Kiddushin is at the end because it follows the Scriptural order that once a woman is divorced, she can get betrothed to any man, this subsequent betrothal symbolised by the placement of Kiddushin.
Both the Babylonian and Jerusalem Talmud have a Gemara on each of the tractates in the Order.