Collagen is a protein that is abundant in our skin and is important in providing strength and stability. It is produced by special cells (called fibroblasts) but over time our skin loses some of its collagen, contributing to skin laxity and sagging.
Elastin is a highly elastic protein in skin and allows many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Again, as we age, our skin loses some elastin which also contributes to sagging and laxity.
Since our faces are constantly subjected to movement & pressure (when we smile, sleep, talk, shout, cry, laugh or sing) the loss of elastin and collagen really can take its toll.