No, embalming is not required by law except under certain circumstances (for example, when shipping the body to another state). Under federal rules, a funeral home may not embalm a body (or charge for it) without authorization from the family.
Embalming disinfects the body and replaces certain fluids with chemicals. This helps preserve the body for a few days so that the deceased may be viewed before burial or cremation. If you select embalming, a funeral director will attend to it personally, professionally, and with care. The funeral director will advise you in this matter. Cosmetics, hair styling, dressing, and casketing are additional options as well.