There are two types of tallit or tallis.
One is the tallit gadol (pictured here). The tallit gadol is a large rectangular shawl. It is usually made of wool, cotton, or synthetic fibers.
In the four corners of the shawl, there are strings tied in a specific pattern called tzitzit. It is usually white with stripes along the edges or throughout. It may also have an embroidered collar. Traditionally, men wear a tallit over their clothes during morning services and on Yom Kippur.
In non-Orthodox communities, some women may also wear a tallit. In some communities, men only wear the tallit gadol after marriage or bar mitzvah.
A short blessing is usually said before putting on a tallit.
The other kind of tallit is the tallit katan. This tallit is also commonly referred to as tzitzit. It may be worn under or over clothing.
It is mostly observant and Orthodox Jewish men and boys who wear the tallit katan.
The tallit comes from the mitzvah (commandment) to wear fringes on the four corners of one’s clothes. Today, because most people do not literally wear four-cornered clothes, they wear the tallit to fulfil this commandment.
Text adapted from English Wikipedia, Creative Commons Attribution-ShareAlike License 4.0.