A kippah (Hebrew: ëÄÌôÈÌäý, also kipah, kipa, kippa, plural kippot; Yiddish: éàÇøîì÷ò, yarmlke, yarmulke, yarmulka, yarmelke, less commonly called kapel) is a thin, usually slightly-rounded cloth skullcap worn by observant Jews (normally men, but not always).
The kippah was traditionally worn only by men (women covered their heads more completely with scarves, hats, or wigs). Today, some non-Orthodox women wear a kippah as well. Some Jews wear kippot only while praying, making blessings, or studying Jewish religious texts; more traditional Jews wear kippot the entire day, making sure not to walk more than four cubits (about two meters) without a head covering, especially outside.
Most head coverings are acceptable according to halakha (Jewish law) because there is no Jewish law regarding head coverings. A kippah is a convenient alternative due to its compactness and lightness; it has become identified as a symbol of Judaism in the last century. Haredi men, who mostly wear large black cloth or velvet yarmulkes, often wear fedoras with their yarmulkes worn underneath. The double head-covering has Kabbalistic meaning to the Hasidim, especially.
https://en.wikipedia.org/wiki/Yarmulke#Traditions
