Endosomes are membrane-bound compartments within cells that play a crucial role in the transport and sorting of molecules. They form when the cell membrane engulfs extracellular material, creating a pocket that pinches off to become an endosome. These structures help in processing nutrients, recycling receptors, and degrading unwanted substances. There are different types of endosomes, including early endosomes and late endosomes, which have distinct functions. Early endosomes are involved in sorting incoming materials, while late endosomes are more focused on degradation and recycling. The proper functioning of endosomes is essential for cellular health and is linked to various processes, including cell signaling and immune response.