Baal Keri

a common occurrence

eighteen decrees, bread of non Jews, cheese, oil, daughters, semen, urine, Baal Keri laws, impurity of lands outside Israel, eating or drinking foods of impurity, rules about mikveh, holy scrolls are impure, unwashed hands, tevul yom, liquids that made other items impure, giving a non Jew his purse to carry on Shabbos, zav not eating with a zavah, items covering an impurity spreads the impurity, harvesting grapes in a bais hapras, mikveh water unwittingly collected in a pipe, wine, vinegar, brine and sauce from fish, preserves, cooked foods, salted foods, split kernels, foreign languages, testimony of idolators, their gifts, sons, and daughters, and their bikkurim

requires immersion in a mikveh?

Torah study partially permitted and partially forbidden