What is tzitzit and when is it worn?

Tzitzit are fringes the Torah commands on any garment with four corners (Bamidbar 15:37–41; Devarim 22:12). They are meant to remind the wearer of all the mitzvot. A man who wears a four-cornered garment must attach tzitzit to it (Shulchan Aruch, Orach Chaim 10:1). The custom is to wear a tallit katan under or over the shirt all day, and a large tallit for morning prayers.

The mitzvah applies by day, not at night (OC 18:1). The strings must be spun and made specifically for the mitzvah (OC 11:1). Before the blessing, you check that the strings are intact (OC 8:9). The blessing on the large tallit is "lehitatef ba-tzitzit" (OC 8:5). On a tallit katan, the Rema prescribes "al mitzvat tzitzit" (Rema, OC 8:6), a distinct blessing. Women are exempt, because it is a time-bound mitzvah (OC 17:2).

The tallit katan is put on in the morning, and many hold the fringes and kiss them during the third paragraph of the Shema (OC 24:4).

A Beit Din may ask a male candidate: what makes a garment need tzitzit, when is the tallit worn, and which blessing is said? It may ask a female candidate why she is exempt.

A common mistake: putting on tzitzit without checking them. If a string is torn or missing, the tzitzit may be invalid. Ask a rabbi when a string is damaged instead of assuming it is still fine.