The secretion of proteins, lipids, and carbohydrates to the cell surface is essential for plant development and adaptation. Secreted substances synthesized at the endoplasmic reticulum pass through the Golgi apparatus and trans-Golgi network (TGN) en route to the plasma membrane via the conventional secretion pathway. The TGN is morphologically and functionally distinct from the Golgi apparatus. The TGN is located at the crossroads of many trafficking pathways and regulates a range of crucial processes including secretion to the cell surface, transport to the vacuole, and the reception of endocytic cargo. This review outlines the TGN's central role in cargo secretion, showing that its behavior is more complex and controlled than the bulk-flow hypothesis suggests. Its formation, structure, and maintenance are discussed along with the formation and release of secretory vesicles.