Many people only know the collective term "vital collagen", in fact, it is a large family composed of a variety of glycoprotein molecules. The genes encoding these molecules change into different types according to different combinations, nourishing various body parts.
The most abundant vital collagen in the human body is type I, II, III, and IV, each of which has a different distribution and function.
The most widely distributed and most abundant type I, accounting for about 85% of the vital collagen in the human body. It’s a type of support fiber, like concrete in construction, that reinforces the build-up in bones, ligaments and muscles, making them more resilient while also keeping the skin moisturised.
Also among the supporting fibers is type II collagen, a small-diameter, criss-crossing strip of fibers that provides a flexible and strong support, and most of our hyaline cartilage is made up of it.

Type III collagen forms a fine network of fibrils and is widely distributed in tissues that need to be stretched, such as the uterus, lungs, arteries, and kidneys, with great distensibility.
The content of type III collagen in the newborn's body is extremely high, but the adult dermis has basically no ability to synthesize type III, and can only synthesize type I.
Type IV collagen is a non-fibrous network structure, which is the main component of the basement membrane of the skin, and also undertakes the great job of "scaffolding".