It's hard to understand why cuticles are so important unless you know their purpose. Cuticles are just one of several structures that keep your fingernails strong and healthy.
But what exactly is a fingernail? Fingernails are made of layers of keratin, a protein that's also found in your skin and hair. Horses have keratin in their hooves. Rhinoceros horns are made of keratin, too, but it's much thicker than the nails found on your body. The biggest and most obvious part of your fingernails -- the part that you trim -- is called the nail plate. Nail folds are the skin that borders your nail plate on three sides. The term nail bed refers to skin just beneath the nail plate.
Cuticles (also called the eponychium) overlap your nail plate at the bottom your nails. As the cells that make up your fingernails age, they harden. Then they're pushed out from under your cuticles by newer cells, and you see the older cells that make up the visible portion of your fingernails.
Your cuticles aren't a pointless part of your finger structure. They help shield new keratin cells from harm as they age and add length to your fingernails. The manner in which cuticles overlap your nail plate also helps seal the gap between your skin and nails. Without this seal, your fingers would be more susceptible to intrusion and subsequent infection by bacteria and viruses.
Many people use specially designed cuticle cutters to trim their cuticles. Usually they do this to neaten the overall appearance of their fingers and hands. The cuticles are soaked in warm water or cuticle-softening chemicals to soften them, and then sharp, stainless-steel cuticle cutters are used to trim back the thickened portion of the cuticles to make them less obvious and more uniform.
Using great care, some people successfully remove the tips of their cuticles where there are no living cells without harm. However, cutting or biting into the portion of the cuticle -- containing living or dead cells -- that's protecting the developing nail plate can cause paronychia, an infection around the base of the nail fold.
Paronychia may manifest itself in symptoms such as pain, swollen and reddish tissues and pockets of yellowish pus. Warm water soaks and antibiotic creams often defeat these infections, but if they worsen, oral antibiotics may be necessary.