Lip balm is a substance put on the lips to give relief to dry, or chapped, lips. It may also be used to help soothe certain other situations, such as cold sores. The balm may be made with any number of ingredients, but usually includes something like petroleum jelly or beeswax, as well as scented oils, and sometimes medicinal herbs or medicinal compounds. It can also have things like vitamins and minerals included, in theory to help support the health of the lips, and many types include sunscreen to help prevent sun damage to the sensitive skin on the lips.
Unlike many other areas of the epidermis, the lips have no oil glands in them, and so they do not naturally produce oils to keep the skin moisturized. At the same time, the layer of skin on the lips is extremely thin, and prone to all sorts of damage. Before turning to lip balm, there are a number of passive steps that can be taken to try to reduce dryness, chapped lips, and damage. If these steps fail to take care of the problem, however, lip products can be a good solution.
One thing that can exacerbate the problem of chapped lips is constantly licking them. Although this may feel like it is moisturizing the lips, by putting saliva on them, it in fact makes the problem worse. It winds up being a vicious circle, as lips become more chapped and irritated, most people lick them more in response, which in turn makes them ever more chapped and irritated. Chewing on the lips as a nervous habit can also damage them and lead to chapping. Similarly, extreme cold and extreme heat can dry out and crack the lips, and severe wind can cause serious damage to them.
There are two main forms of distribution for lip balm: a tub or a stick. The tub, often no more than a tiny little container, is meant to be applied with the tip of a finger. The stick, which is similar in many ways to a tube of lipstick, can be applied directly to the lips. One of the most famous types that comes in the stick form is ChapStick™, and many people refer to all types of stick lip balm by this name, even though it is technically a trademark.
The point of this product is fundamentally to help protect the lips from moisture loss, so the active component is an occlusive like petroleum jelly or bees wax. In fact, the first ones were simply made out of earwax, and in recent years some natural-product proponents have begun suggesting a return to earwax-based products, as it is organic, and easy to use. The taste, however, is typically not pleasant, and many people find it unpalatable.
Many forms of lip balm are treated with flavor agents, often different berry or fruit flavors, to mask the existing flavor or add to the empty flavor of petroleum jelly. Some products may also add some sort of color to the lips, although it should not be mistaken for lip gloss. Lip gloss is similar, except that it is not formulated to lock in moisture, existing instead just to add color or shine to the lips.