Red string (Kabbalah)
Wearing a thin scarlet or a crimson string (Hebrew: חוט השני, khutt hashani) as a type of talisman is a Jewish folk custom which is practiced as a way to ward off misfortune which is brought about by the "evil eye"  (Hebrew: עין הרע). The tradition is popularly thought to be associated with Kabbalah and religious forms of Judaism. The red string itself is usually made from thin scarlet wool thread. It is worn as a bracelet or band on the wrist of the wearer. Biblical history
A scarlet thread, tied about the wrist, is mentioned in Genesis 38. Tamar becomes pregnant by her father-in-law, Judah, and gives birth to twin boys. The following verses about this event are taken from the King James Bible:

As early as Rabbi Shmuel ben Hafni Gaon, Jewish commentators noted that the placement of a red string on one's hand may be a good omen. Some sources imply it may even be placed around a finger. Some early Jewish commentators (such as Aggadas Bereishis) write that Joseph's coat (given to him by Jacob) was actually the exact same as the coat of the other Tribes, just that Jacob placed a red string on the cuffs. Through the ages
There is no written mention in the Torah, Halacha, or Kabbala about requiring the tying a red string around the wrist. Though sources mention red strings as a good omen, it is not evident if they were widely worn. The only case we find a public exhortation to wear red strings is in the 1490s: When Jews were not allowed to wear Tefilin, Rabbi Abraham Saba recommended Jews to wear a red string on their hands (to remember the commandment of Tefilin). Modern trend

Today in Israel, it is common to see elderly women peddling scarlet thread for pilgrims and tourists, especially in the Old City of Jerusalem. Outside of Israel in the late 1990s the red string became popular with many celebrities, including many non-Jews including Madonna and her children, Leonardo DiCaprio, and Michael Jackson, and later by Ariana Grande and Rishi Sunak. The wider popularity is often linked to Philip Berg's  Kabbalah Centre. It also gained a surge in sales for Madonna according to editors of  Changing Fashion: A Critical Introduction to Trend Analysis and Cultural Meaning (2007). See also 
 Apotropaic magic
 Hamsa
 Practical Kabbalah
 Kautuka
 Raksha Bandhan
 Martenitsa

References

Book sources

External links

Explanatory
 Beliefnet: Why the Red String? Teman, Elly. 2008. "The Red String: A Cultural History of a Jewish Folk Symbol," in: Bronner, Simon J. (ed. ), Jewishness: Expression, Identity, Representation, Inaugural volume in book series on Jewish Cultural Studies, Oxford: Littman Library of Jewish Civilization. Ask the Rabbi: Red Strings

Critical
Vice: "Why Celebrities Stopped Following Kabbalah" 
Michael Laitman: Practical Kabbalah has no use for red strings

Amulets
Bracelets
Kabbalah