Arranged by the simanim of Shulchan Aruch, Yoreh De'ah. Each article gives you the practical halachah first, then the sources it rests on.
Why does every woman today count seven clean days, even for light bleeding? The Torah sources for niddah and zavah, the chumra of Rabbi Zeira, and why it cannot be set aside.
A woman becomes a niddah through uterine bleeding accompanied by hargashah. The three sensations the poskim describe, the three contemporary approaches, and when a bedikah is required.
Beyond bleeding with a hargashah, the Sages ruled that a stain can also render a woman a niddah. The five conditions a stain must meet, and why asking beats being stringent on your own.
Only a stain larger than a gris renders a woman temei'ah. What a gris actually is, the source in the Gemara, the ruling of the Shulchan Aruch, and how to measure one with a coin.
Rashi's explanation of why a stain on colored fabric cannot render a woman temei'ah, why colored underwear is recommended, the off-white question, and striped fabric.
Could uterine blood plausibly have reached this spot? The places where a stain renders a woman temei'ah, the sources in Masechet Niddah, and the ruling of the Shulchan Aruch.
The five problematic shades of the Mishnah, the loss of expertise in distinguishing shades of red, the permitted colors according to the Tur and the Shulchan Aruch, and where brown stands.
Blood from a wound does not render a woman temei'ah. Where the wound has to be, what to ask the doctor before an IUD insertion or a biopsy, and the dispute between the Shulchan Aruch and the Rema.
Before applying the criteria of a stain, establish whether this is a halachic stain or halachic bleeding. The distinction, and the three contemporary approaches to hargashah.
A bedikah cloth, immediately after relations, and immediately after urination: three cases in which halachah assumes a hargashah occurred even if the woman noticed nothing.
The dispute between Rabbi Meir and Rabbi Yosei over blood found after urination, the four conditions of Rabbeinu Chananel, and why the question is largely moot today.
After urination, after an object has been inserted, and immediately after relations. What to do in practice so that an ordinary stain stays an ordinary stain.
Siman 190 in one picture: the Torah basis, the six criteria of a stain that renders a woman temei'ah, the stain-versus-bleeding distinction, and the three cases where a hargashah is assumed.
Why the harchakot exist, the tension in Chazal between pat b'salo and the need for a further fence, and what kalut rosh actually asks of a couple.
The three most basic harchakot: avoiding kalut rosh, not passing objects, and the Ashkenazi–Sephardi dispute over throwing. Plus carrying something heavy together and handing over a baby.
Why passing objects is forbidden even when touching is unlikely, what to do in public, handing over a baby, carrying something heavy together, and the sources behind each ruling.
While a woman is nidda she keeps doing all her usual work, with three exceptions: making her husband's bed, pouring his wine, and washing him. Why these three, and how each works in practice.
What happens when one spouse is ill and touch is forbidden? Why the Shulchan Aruch treats a sick husband differently from a sick wife, and what to arrange before a planned surgery.
A husband may not send his wife a glass of wine, which raises a question at kiddush. Five permitted ways through it, and whether a couple should use the same one all month.
What a hefsek taharah accomplishes, whether the obligation is biblical or rabbinic, and why that question matters in practice.
The full practical walkthrough: the window before sunset, the morning backup, washing and waiting ten minutes, checking the color, and which cloths are acceptable.
Why study the development of the halachah rather than just the bottom line, the dispute in the Mishnah over the earliest day, and the Shulchan Aruch's ruling on a hefsek on the first day of bleeding.
The ideal window is late afternoon, a morning backup hefsek is valid, and the hefsek must precede sunset. Why that deadline matters, from the practice of the Kutim.
The preparations the Rokeach describes, why to wait a few minutes after washing, what the folds and crevices requirement means, how deep the bedikah goes, and today's practical ruling.
The two criteria from the Gemara, material and color, the three options the Shulchan Aruch accepts, what to do when no bedikah cloths are available, and why a tampon will not do.
The Gemara's rhetorical question that the Rashba turned into a practical solution, when a moch is obligatory, and why health comes before keeping it in place too long.
The custom from the Rokeach, how the Shulchan Aruch and the Rema read it differently, and what that means today for white underwear, colored underwear and white sheets.
The count begins the day after the hefsek taharah, never on the same day. A worked example, why the mistake invalidates immersion, and an easy way to remember.
The source at Matan Torah, why this tum'ah interrupts the seven clean days, and the dispute between the Shulchan Aruch and the Rema behind the Sephardi four days and Ashkenazi five.
Two bedikot a day lechatchilah, days 1 and 7 b'dieved, the Nishmat approach of three, and why awareness that you are counting matters as much as the bedikot.
The four steps of becoming tehorah, which colors on a bedikah cloth are acceptable, and why finding a rav who is baki b'mar'ot matters so much.
Simcha Babaev