The document summarizes key components and cells that make up the extracellular matrix (ECM). It discusses the main biopolymer collagen and cell surface proteins that enable cell-cell and cell-ECM connections. It describes specialized ECM-producing cells like fibroblasts that secrete macromolecules and immune cells that patrol the ECM. The major ECM molecules are then outlined, including collagens, elastin, proteoglycans, hyaluronan, and adhesive glycoproteins. The basal lamina, a thin ECM layer that supports epithelia, muscles and nerves, is also summarized.