A chain of 2 to 50 amino acids. Amino acids are the building blocks of proteins, so peptides are usually added in skincare to build more complex proteins such as collagen. Peptides are naturally present in the skin, meaning that the skin knows how to use them. Peptides can help boost collagen production, which can help reduce the appearance of fine lines and wrinkles. They can also help improve skin elasticity, firmness, and hydration. Some peptides may also help to reduce redness, improve skin tone and texture, and even out skin pigmentation.