You might recognize it as an ingredient in your favorite body lotion or perhaps noticed supplements in the vitamin aisle that feature it. But what is collagen, exactly — and how can you incorporate it into your life?. Collagen is the most abundant protein in our bodies, especially type 1 collagen. It’s found in muscles, bones, skin, blood vessels, digestive system and tendons. It’s what helps give our skin strength and elasticity, along with replacing dead skin cells.