Collagen is one of the most abundant proteins in the body and it makes up a large part of our skin, hair and nails. Technically a polypeptide, collagen contains a mixture of amino acids like proline and glycine, which are found in all connective tissue within the body (including vital organs!). 
What is Collagen?
Collagen is a long-chain amino acid and the most abundant protein in the body. It is composed of the individual amino acids Glycine, Proline, Hydroxyproline and Arginine and in nature is found exclusively in animal tissue, especially bones and connective tissue.
It is what is responsible for giving skin elasticity, hair its strength, and connective tissue its ability to hold everything in place. In fact, the collagen protein makes up 30% of the total protein in the body, and 70% of the protein in the skin!
Other Benefits
Though not as immediately noticeable, there are other benefits that might be even more important. For instance, collagen has been studied for its role in:
Bone and Joint Health– Collagen may be beneficial to bones and joints in the same way it benefits the skin. By helping the body’s natural production of collagen and providing a bioavailable source of these amino acids, collagen may improve bone and joint health over time. In fact, a double-blind, placebo study showed significant improvement in joint pain. 
Hormone Balance- Emerging research shows that the specific amino acids in collagen may help improve the amino acid balance in the body and support the body’s natural hormone production.
Digestion– As mentioned, gelatin and collagen may help coat the digestive tract and improve digestion, and the consumption of gelatin is often recommended on gut-specific diets like GAPS and SCD.