Sialic acids are negatively charged, nine-carbon monosaccharides found at the terminal ends of glycoproteins and glycolipids, playing key roles in cellular communication and function. Sialylation, a post-translational modification, involves the covalent attachment of sialic acid to oligosaccharides and glycoproteins, providing electrostatic repulsion and serving as a receptor for biological signaling pathways. Sialylation is involved in various pathophysiological processes and has potential therapeutic applications in cancer, stroke, antiviral strategies, and central nervous system disorders. Sialylation is regulated by sialyltransferases and sialidases, with sialyltransferases adding sialic acid to glycans and sialidases removing it. Sialylation influences immune responses, complement activation, and leukocyte trafficking. It also plays a role in neurological disorders, such as Alzheimer's disease and multiple sclerosis, and in cardiovascular diseases, where it affects atherosclerosis. Sialylation is involved in viral infections, with sialic acid interactions influencing viral binding and replication. Therapeutic strategies targeting sialylation include sialidase conjugates, sialyltransferase inhibitors, and antibodies against sialic acid receptors like SIGLECs. These approaches aim to enhance immune responses, reduce tumor progression, and treat neurological and cardiovascular diseases. Sialylation is a promising target for novel therapeutic interventions in various diseases.Sialic acids are negatively charged, nine-carbon monosaccharides found at the terminal ends of glycoproteins and glycolipids, playing key roles in cellular communication and function. Sialylation, a post-translational modification, involves the covalent attachment of sialic acid to oligosaccharides and glycoproteins, providing electrostatic repulsion and serving as a receptor for biological signaling pathways. Sialylation is involved in various pathophysiological processes and has potential therapeutic applications in cancer, stroke, antiviral strategies, and central nervous system disorders. Sialylation is regulated by sialyltransferases and sialidases, with sialyltransferases adding sialic acid to glycans and sialidases removing it. Sialylation influences immune responses, complement activation, and leukocyte trafficking. It also plays a role in neurological disorders, such as Alzheimer's disease and multiple sclerosis, and in cardiovascular diseases, where it affects atherosclerosis. Sialylation is involved in viral infections, with sialic acid interactions influencing viral binding and replication. Therapeutic strategies targeting sialylation include sialidase conjugates, sialyltransferase inhibitors, and antibodies against sialic acid receptors like SIGLECs. These approaches aim to enhance immune responses, reduce tumor progression, and treat neurological and cardiovascular diseases. Sialylation is a promising target for novel therapeutic interventions in various diseases.