Is the kippah a commandment from the Torah?

No. It is a custom from the time of the Talmud that later authorities treated as obligatory for men at all times, especially during prayer and blessings.

What is the difference between kippah and yarmulke?

None – kippah is the Hebrew word and yarmulke the Yiddish one. Kippah is common in Israel; yarmulke among Ashkenazi Jews abroad.

May a non-Jew wear a kippah?

Non-Jewish visitors are customarily asked to cover their heads in a synagogue or at a Jewish ceremony as a sign of respect, and doing so is welcome.

Does the colour or style matter?

Not in Jewish law. Style is a matter of community and personal preference.

Kippah (yarmulke) – why Jewish men cover their heads כִּפָּה

A kippah (Hebrew) or yarmulke (Yiddish) is the small cap worn by Jewish men as a sign of reverence for God. It is not one of the Torah’s commandments but an ancient custom that became a firm norm of Jewish law.

The source

There is no verse commanding a head covering. The Talmud tells of Rav Huna son of Rav Yehoshua, who would not walk four cubits bareheaded, saying “the Divine Presence is above my head” (Kiddushin 31a), and of a mother who told her son to cover his head “so that the fear of Heaven may be upon you” (Shabbat 156b). From these grew the practice of covering the head at all times.

The Shulchan Aruch rules that one should not walk four cubits bareheaded (Orach Chayim 2:6) and that the head must be covered when mentioning God’s name and in prayer (91:3). Later authorities, such as the Taz, treated the custom as binding because it had become a mark of Jewish identity.

Styles and what they say

Any covering will do halachically, but the style often reflects a community: black velvet or cloth among many Haredi and Yeshiva Jews, knitted kippot among Religious Zionists, large round colourful caps among Bukharan and some Sephardi Jews. Many men also wear a hat over the kippah for prayer.

Women and the kippah

In Orthodox practice married women cover their hair, which is a different law, and do not wear a kippah. In some non-Orthodox communities women wear one by choice.

Sources

Talmud and halachic sources

Talmud, Shabbat 156b; Kiddushin 31a
Shulchan Aruch, Orach Chayim 2:6 and 91:3; Mishnah Berurah 2:11

Frequently asked questions

Is the kippah a commandment from the Torah?: No. It is a custom from the time of the Talmud that later authorities treated as obligatory for men at all times, especially during prayer and blessings.
What is the difference between kippah and yarmulke?: None – kippah is the Hebrew word and yarmulke the Yiddish one. Kippah is common in Israel; yarmulke among Ashkenazi Jews abroad.
May a non-Jew wear a kippah?: Non-Jewish visitors are customarily asked to cover their heads in a synagogue or at a Jewish ceremony as a sign of respect, and doing so is welcome.
Does the colour or style matter?: Not in Jewish law. Style is a matter of community and personal preference.