Here's a breakdown:

* Vesicles: Small, membrane-bound sacs that transport materials within cells.

* Endoplasmic Reticulum (ER): A network of membranes involved in protein synthesis and lipid metabolism.

* Golgi Complex: An organelle that modifies, sorts, and packages proteins and lipids.

* Cell Membrane: The outer boundary of a cell.

Exocytosis is the process where these vesicles, filled with substances destined for export, fuse with the cell membrane and release their contents outside the cell. This is how cells release hormones, neurotransmitters, waste products, and other materials.