Editing Tohorot (section)

==Order of tractates==
According to [[Maimonides]], the traditional reasoning for the order of the tractates is as follows:
* ''Kelim'' is first as it introduces the levels of impurity, and dictates to which object the various impurities apply at all.
* ''Oholot'' follows because it outlines the most serious type of impurity. 
* ''Negaim'' follows because it is next in severity and because, like a corpse, a ''metzorah'' transmits tent-impurity. ''Parah'' follows as it outlines the purification for the severe impurities already dealt with.
* The next stage is lesser impurities (''Tohorot'') and their method of purification which is immersion (''Mikvaot'').
* ''Niddah'' follows as it is also a lesser impurity but it has the extra feature of applying to only a portion of people (i.e. to women).
* ''Makshirin'', ''Zavim'' and ''Tevul Tom'' follow ''Niddah'' based on Scriptural order.
* The next stage down is ''Yadaim'', concerning impurities that are Rabbinic only.
* ''Uktzin'' is last as it is restricted and has no Scriptural source, the laws being derived from the reasoning of the Sages.

''[[The Jewish Encyclopedia]]'', on the other hand, observed that the tractates are arranged in order of decreasing length. 

There is a [[Babylonian Gemara]] only on ''Niddah''. This is because most of the other laws of purity do not apply when the [[Temple in Jerusalem]] is not in existence. The [[Jerusalem Talmud]] only covers four chapters of ''Niddah''.