N-linked glycosylation is a biochemical process where sugar molecules are attached to a nitrogen atom in an amino acid, typically asparagine, within a protein. This modification occurs in the endoplasmic reticulum and Golgi apparatus of cells, playing a crucial role in protein folding, stability, and function. The addition of sugar chains can influence how proteins interact with other molecules, affecting their activity and localization. N-linked glycosylation is essential for many biological processes, including cell signaling and immune responses, and is important in the development of therapeutic proteins and vaccines.