Lysosome-related organelles are a diverse group of specialized intracellular membrane-enclosed compartments that exhibit certain characteristics of lysosomes (major membrane-bound digestive structures involved in intracellular degradation of biological materials in all eukaryotic cells). Lysosomes contain a unique collection of digestive enzymes and membrane proteins, maintain an acidic luminal pH, and receive ingested as well as newly synthesized materials. Although most of these features are shared to a certain extent by all lysosome-related organelles, each of these organelles also contains cell-type–specific components responsible for its specialized functions.