Payot

Reason

According to Maimonides, shaving the sidelocks was a heathen practice.

Specifics

The Torah says, "you shall not round off the pe'a of your head (פְּאַת רֹאשְׁכֶם)". The word pe'a was taken to mean the hair in front of the ears extending to beneath the cheekbone, on a level with the nose (Talmud – Makkot 20a). The Mishnah interpreted the regulation as applying only to men. Thus it became the custom in certain circles to allow the hair over the ears to grow, and hang down in curls or ringlets. There is considerable discussion in the halachic literature as to the precise location of the payot and of the ways in which their removal is prohibited.

Yemenite Jews

• Some traditional Yemenite Jews still wear distinctive long and thin twisted locks, often reaching to the upper arm. The actual area where the hair grows and where the ringlet begins is neat and tidy.

Hasidic groups

• Satmar Jews have notably thicker sidelocks. They also tend to tuck their sidelocks behind their ears.
• Belz Hasidim wrap their sidelocks around their ears as many times as necessary without trimming.
• Many Breslov Hasidim wear long twisted locks as did their Rabbi, Nachman of Breslov. However, others wear different styles in line with the teaching of Rabbi Nachman that his followers do not have to have a uniform garb.
• The Chabad-Lubavitch Hasidim's payot are not evident, but they exist. So long as there is hair around the ear and behind it that can be plucked out, that is considered payot.
• Some Gerer Hasidim raise their sidelocks from the temples and tuck them under their yarmulke. Others, especially in Israel, let them hang down.
• The Skver Hasidim twist their sidelocks into a tight coil, and leave them protruding in front of the ear.

Most other Hasidic groups wear their payot down and curled.

Lithuanian groups

The Lithuanian Jews are less influenced by Kabbalistic practises, but still retain sidelocks to a degree, in a small number of variant styles:

• Lithuanian Jews often cut their sidelocks, but leave a bunch of strands uncut, and place them behind the ear; this style is most commonly found among yeshiva students, who sometimes remove the uncut strands when they have grown sideburns.
• The Brisk movement's members brush their hair straight down, usually so that it reaches to the ear lobe; sometimes, some of the sidelock is not cut, and is curled back behind the ear.