Jewish men and boys, usually from early childhood for the tallit katan. Women are exempt, as it is a time-bound commandment.

What is the difference between a tallit and tzitzit?

The tallit is the large prayer shawl; “tzitzit” is the name of the fringes and, colloquially, of the small fringed undergarment (tallit katan).

Why are some tzitzit blue?

The Torah requires a thread of tekhelet. Some today use a dye from the murex snail, which they identify as tekhelet; others wait for broader consensus and wear white.

Are tzitzit worn at night?

The obligation applies to daytime garments; many keep wearing the tallit katan at night anyway.

Tzitzit – the fringes on the four corners צִיצִית

Tzitzit are the knotted fringes the Torah commands on any four-cornered garment. Jewish men fulfil the mitzvah with the tallit worn at prayer and with a small fringed garment (tallit katan) worn all day.

The source

“They shall make fringes on the corners of their garments… and you shall see it and remember all the commandments of the Lord” (Numbers 15:38–39; see also Deuteronomy 22:12). This passage is the third paragraph of the Shema, so it is recited twice a day. The Talmud says that seeing the tzitzit brings a person to remember and keep all the commandments (Menachot 43b).

How they are made

Four strings are threaded through each corner and folded to make eight, then tied with double knots and windings.
The commandment applies by day (Menachot 43a); the blessing on the tallit is said after dawn.
Originally one string was dyed tekhelet, a blue from a sea creature. Its identity was lost for centuries; today some wear blue strings from the murex snail, while most still wear white only.

Sephardi and Ashkenazi customs

Among many Eastern-European Ashkenazim a man begins to wear a large tallit for prayer after his wedding, while Sephardim and German Jews do so from bar mitzvah or earlier. Ashkenazim usually let the strings of the tallit katan hang out, following the Mishnah Berurah (8:26); many Sephardim tuck them in, following kabbalistic custom. The winding patterns between the knots also differ (Ashkenazi 7-8-11-13, Sephardi and Chabad variants).

Sources

דַּבֵּר אֶל־בְּנֵי יִשְׂרָאֵל וְאָמַרְתָּ אֲלֵהֶם וְעָשׂוּ לָהֶם צִיצִת עַל־כַּנְפֵי בִגְדֵיהֶם לְדֹרֹתָם וְנָתְנוּ עַל־צִיצִת הַכָּנָף פְּתִיל תְּכֵלֶת וְהָיָה לָכֶם לְצִיצִת וּרְאִיתֶם אֹתוֹ וּזְכַרְתֶּם אֶת־כָּל־מִצְוֺת יְהוָה וַעֲשִׂיתֶם אֹתָם וְלֹא־תָתֻרוּ אַחֲרֵי לְבַבְכֶם וְאַחֲרֵי עֵינֵיכֶם אֲשֶׁר־אַתֶּם זֹנִים אַחֲרֵיהֶם
Numbers 15:38–39
גְּדִלִים תַּעֲשֶׂה־לָּךְ עַל־אַרְבַּע כַּנְפוֹת כְּסוּתְךָ אֲשֶׁר תְּכַסֶּה־בָּהּ
Deuteronomy 22:12

Talmud and halachic sources

Talmud, Menachot 38a–44a
Shulchan Aruch, Orach Chayim 8–24

Frequently asked questions

Who wears tzitzit?: Jewish men and boys, usually from early childhood for the tallit katan. Women are exempt, as it is a time-bound commandment.
What is the difference between a tallit and tzitzit?: The tallit is the large prayer shawl; “tzitzit” is the name of the fringes and, colloquially, of the small fringed undergarment (tallit katan).
Why are some tzitzit blue?: The Torah requires a thread of tekhelet. Some today use a dye from the murex snail, which they identify as tekhelet; others wait for broader consensus and wear white.
Are tzitzit worn at night?: The obligation applies to daytime garments; many keep wearing the tallit katan at night anyway.