What are vesicles and what do they do?

Vesicles can be found inside or outside cells. They are made of a bilayer of lipids and can contain cytoplasm or liquid. They are either excreted by the cells to signals to other cells or are formed inside the cells when the cells engulf something from the outside (transport role). Vesicles can have a variety of function and have different names based on those functions: the vacuoles contain mostly water and are mostly found in plant cells, lysosmes inside cells digest other cells and organelles, transport vesicles that moves molecules between the endoplasmic reticulum and the Golgi apparatus, secretory vesicles and extracellular vesicles.