Broadly, nails can be defined as the protective caps of your finger and toe tips. As hands and feet are the most commonly used organs in a human body, fingers and toes are more prone to injuries and shocks. Nails are the nature's boon to mankind to prevent the fingers and toes from direct injuries and shocks.

The finger tips and toe tips are highly sensitive areas as these areas are rich in nerve endings. Therefore an injury to the tips of the toe or a finger can be very painful and at the same time serious. A nail, which in fact is a type of skin itself, cover and protect these delicate parts of the human body.

The outmost layer of a nail which is called the nail plate consists of dead cells and is therefore immune to mild shocks and injuries. The main ingredients of a nail plate are keratin, a fibrous protein, and calcium. It is therefore very hard in nature which makes it an ideal protective layer for finger and toe tips.

The nail plate rests on the nail bed. Nail bed is another thick layer of the skin. However it consists of living cells and it holds the nail to your body. Nails are transparent in nature and increased blood circulation through the nail bed gives it a pink shade. Therefore finger and toe nails which are pink in colour and without any deformity are termed to be the signs of good health. A protein rich diet will help you maintain strong and healthy nails.

Nails can help in protection and helps in being a part of healthy and disease free person. The uses of nails are:

• Apart from providing protection to your finger and toe tips, nails help you to grip objects more firmly and efficiently. Toe nails protect you from banging your toes against hard objects.
• Nails also play an important role in diagnosing various diseases at its initial stages. The change in colour, texture, and appearance of nails often denotes abnormalities in the functioning of internal organs and can go a long way in identifying such abnormalities at the threshold. Even life threatening disease like cancer can be detected by closely monitoring the changes occurring to one’s nails. Needless to mention timely detection of cancer is crucial in its cure.
  
• The change in colour, texture and appearance of nails may be hereditary or due to other simple reasons. Therefore there is no need to panic on simple identification of some abnormalities regarding your nails. Consult a qualified physician in case of nail deformities and he will be able to guide you and diagnose serious troubles if any and suggest a treatment plan accordingly.
• Apart form biological importance; nails have an important role to play in the outward appearance of the person. A person with clean, healthy finger and toe nails creates an impression among others to be upright, punctual, gentle and energetic. Personal cleanliness of a person can often be correctly assessed by verifying the cleanliness of his toe nails. Among women, beautiful long nails are considered to be signs of beauty and glamour from time immemorial.
  

Source: ultimate-cosmetics.com/guides/nail-care/