Glycoproteins are molecules that consist of proteins with carbohydrate chains attached to them. These carbohydrates, or sugars, can influence the protein's structure and function, playing essential roles in various biological processes. Glycoproteins are found on cell surfaces and in bodily fluids, where they help with cell recognition, signaling, and immune responses. In addition to their role in cell communication, glycoproteins are important in the development of vaccines and therapeutic drugs. For example, the human immunodeficiency virus (HIV) uses glycoproteins to attach to and enter human cells. Understanding glycoproteins is crucial for advancements in medicine and biotechnology.