About one third of all of the protein in your body is collagen. Collagen is a major structural protein, forming molecular cables that strengthen the tendons and vast, resilient sheets that support the skin and internal organs. Bones and teeth are made by adding mineral crystals to collagen.
User-generated content. User-generated content (UGC), alternatively known as user-created content (UCC), is any form of content created by users of a system or service and made available publicly on that system.
1 The lower the U-factor, the better the window insulates. (EPA requires that the U-Factor for ENERGY STAR labeled products is certified and listed on the product label.)  Solar Heat Gain Coefficient (SHGC) measures the fraction of solar energy transmitted and tells you how well the product blocks heat caused by sunlight.