"1. To make a 'fence around the law,' for those who know it and for those who may violate it inadvertently;
2. To keep one involved in the faith through its rituals and to keep one from falling into bad habits or indifference;
3. To instill a sense of community and inhibit assimilation, which is warned against in several passages of the Torah;
4. To glorify the commandments in ways that go beyond the basic requirements, such as the making of certain foods or lavish ceremonial objects for the home or synagogue;
5. To provide a mechanism by which Jewish law may be applied and updated,"
(pg. 1 of The Book of Customs by Kosofsky)