"...on the tenth of the month, you shall afflict your souls and do no work at all...for on that day God will forgive you and cleanse you, that you may be clean from all your sins before God" (Leviticus 16:29-30).
How does one “afflict one's soul”? The oral law enumerates the following five restrictions:
Fasting (No Eating or Drinking) - From sunset on the eve of Yom Kippur until nightfall the next day, it is forbidden to eat or drink. However, those who are ill, as well as pregnant and nursing women, should and, in some cases, must, eat on Yom Kippur, as decided by their rabbi in consultation with their doctor,. In such cases the rabbi should also be consulted about specific details of eating on Yom Kippur. Additionally, girls below the age of 12 and boys below the age of 13 are not required to fast.
Washing - During the fast, one may not wash for pleasure, but one may wash to get rid of dirt or when preparing food (e.g. for children). One may also bathe a baby.
Anointing - It is forbidden to anoint oneself with oil. Thus, the use of perfumes, liquid or cream make-up, suntan lotion, and other such items is prohibited.
Wearing Leather Shoes - During the fast it is forbidden to wear leather shoes. Some people wear only socks, but others wear shoes of canvas or other non-leather materials (i.e. crocs).
Marital Relations - It is forbidden to have marital relations.
It may seem that refraining from the above actions would make one focus on the body, due to hunger or thirst, or the discomfort of not washing. However such discomforts are temporary and, in fact, turn one’s attention back to the importance of the day and the fact that we can transcend physical discomfort in order to connect with the spirit of the day.