A Kippah or yarmulke is a head covering worn by Jewish men. Some men will wear their kippah all the time while other Jewish men will only wear one while at synagogue or a special occasion which shows respect toward the host and occasion like a Shabbat lunch or a Passover Seder.
Wearing a kippah is said to be a reminder of G-d or the higher being. According to Exodus 28:4, wearing a kippah in temple is required. The Code of Jewish Law also states that a head covering should be worn always in public.
Obviously there are certain times one does not wear a kippah. While playing sports, many men will remove their head covering as it may fall off and hitting the ground is not respectful. Every time the kippah falls to the ground, it must be kissed so that may be hard to do while running down a soccer field!
The same goes for swimming or taking a shower; a yarmulke is not worn.
Depending on the environment the man is, covering their head can also be done with a baseball cap. Many men I have known will wear their kippah underneath their baseball cap; as long as their head is covered, this usually qualifies as a head covering. When in synagogue of course, a yarmulke should always be the first choice and the respectful one.
There are many different types of kippahs from handmade ones to suede leather to the cheap nylon ones that stick up. As one of the Rabbi’s I worked with said to the children, “Go out and ask your parents to buy you a real yarmulke otherwise I’ll make fun of you till you do.” There are even kippahs with designs on the suede. I have seen a basketball, hand painted cartoon characters, and smiley faces imprinted on them.
Yarmulkes can be found at any Judaica shop and online.