Transport vesicles are small, membrane-bound sacs that move molecules within cells. They play a crucial role in the cellular transport system by carrying proteins, lipids, and other substances from one part of the cell to another. These vesicles form from the endoplasmic reticulum or Golgi apparatus and can fuse with other membranes to deliver their contents. Once formed, transport vesicles travel along the cytoskeleton, a network of protein filaments that provides structural support and pathways for movement. They ensure that essential materials reach their destinations, such as the plasma membrane for secretion or other organelles for processing.