Many Orthodox Jewish men wear curls on the sides of their heads to be in accordance with an interpretation of a verse in the Torah that prohibits shaving the "corners" of the head. These curled locks are called peyos. They may be worn quite short as long as they are not shaved or removed completely; however, many men prefer to wear them long to distinguish themselves from non-Jews.
The injunction against shaving the peyos is found in the Torah: "You shall not round off the peyos of your head" (Leviticus 19:27). According to Rabbi Shraga Simmons, the peyos also serve several other purposes. Firstly, they prevent the wearer from becoming too occupied with how he looks, leading to the sin of vanity. They also serve as a symbolic separation of the front part of the brain that governs abstract and religious thought and the back part of the brain that controls the earthly functions of the body.
According to Rabbi Joseph Kolakowski, different sects of Judaism wear different styles of peyos. Hasidic Jews wear their peyos in distinctive curls, while some groups like the Belz and Ger let their peyos grow out straight and then tuck the hair behind their ear or underneath their yarmulke.