Proteoglycans are a class of glycoproteins that are heavily glycosylated, meaning they have a high content of carbohydrates attached to their protein core. They are found in the extracellular matrix of cells and play important roles in cell signaling, cell adhesion, and tissue structure. Proteoglycans are composed of a core protein with one or more long chains of carbohydrates called glycosaminoglycans (GAGs) attached to it. These carbohydrates give proteoglycans their gel-like consistency and help to regulate the signaling interactions between cells and their environment. Proteoglycans are involved in various biological processes such as development, wound healing, and inflammation, and abnormalities in their structure or function have been associated with diseases such as cancer, arthritis, and cardiovascular disorders. Research in this area aims to understand the role of proteoglycans in health and disease and to develop new therapeutic strategies targeting these molecules.