Jews wear a kippah, or yarmulke, as a symbol of reverence before God. Traditionally, kippot (the plural of Kippah) are worn only by men, though depending on community and personal customs, women may also choose to wear the head covering.
The kippah is deeply associated with Jewish identity and religious practice. Orthodox men wear them continuously, in both religious and secular settings. Conservative men generally wear them when at synagogue, on High Holy Days and at community events such as weddings and bar and bat mitzvahs. Jews in the Reform tradition may or may not wear the kippah, and women who choose to wear it find the most acceptance within this tradition. The head covering isn't worn during bathing or swimming. It is appropriate at all other times.
The materials and colors of kippot can denote group affiliation and status. A small, black kippah made of silk is considered a "one time use" head covering, as it is often given out at funeral homes to men who don't have a kippah of their own. A large, smooth, black kippah can denote an Orthodox Jew, while a large black felt kippah often signifies a Hasidic Jew. Bright, woven kippot are common in Sephardic communities, and knitted kippot can denote Nationalist Zionist Jews.