Extracellular vesicles are naturally occurring nanoparticles that are released by all cells and serve important roles in physiological and pathological intercellular communication. Extracellular vesicles have promising applications as therapeutic agents, drug targets, delivery vehicles, and biomarkers. However, research progress is hindered by an incomplete understanding of the molecular composition of extracellular vesicles. In particular, the glyco-code remains largely unknown due to technical challenges in extracellular vesicle isolation coupled with high-throughput glycomics. This talk will highlight a glycomics approach to understanding extracellular vesicles with a focus on breast cancer metastasis.