What are tzitzit?

Answer 1

If a Jewish male wears a 4 cornered garment, he is commanded to have tzitzit on each of the corners. Tzitzit are strings that are wrapped and tied in knots. They are worn as a reminder of the commandments (Numbers 15:37-41).

Answer 2

If a Jewish male wears a 4 cornered garment, he is commanded to have tzitzit on each of the corners. Tzitzit are strings that are wrapped and tied in knots. They are worn as a reminder of the commandments (Numbers 15:37-41): "Speak to the Children of Israel, that they shall make themselves tzitzit (string-fringes) on the corners of their garments throughout their generations...when you see them, you shall remember all of God's commandments so as to keep them. You will then not stray after your heart and eyes which have led you to immorality. You will thus...be holy to your God."

The obligation only applies to four-cornered garments, which may have been common in Biblical times but are not common anymore. In order to fulfill the relevant Torah-verses, religious Jews wear a garment that is specifically made to have four corners. This is known as the "Tallit Katan" and is usually worn under the shirt, often with the tzitzit hanging out so they can be seen.
The garment is a single-piece, untailored cloth with a hole for the head and small holes at each of the four corners. In each hole, specially spun wool strings are tied. One string (called the "shamash") is longer and wraps around the others, with a series of knots in between.
There is a specific procedure for tying the knots of the tzitzit, filled with religious significance. The tying pattern symbolizes the 613 commandments in the Torah.

See also the related Link.

Examples of the Torah's commands