Dynamin, a founding member of the dynamin-like GTPase (DLP) family, plays a critical role in endocytic membrane fission. Complementary approaches, including live cell imaging, cell-free studies, X-ray crystallography, and genetic studies in mice, have advanced our understanding of dynamin's mechanisms, essential roles in cell physiology, and the specific functions of different dynamin isoforms. Dynamin assembles into helical polymers at the necks of budding vesicles, promoting membrane fission through GTPase-dependent conformational changes. Three dynamin isoforms are expressed in mammals, each with distinct expression patterns and functions. Dynamin interacts with various proteins, including SH3-domain-containing proteins, and binds to phosphoinositides via its pleckstrin homology (PH) domain. The PRD region of dynamin interacts with SH3 domains to coordinate its function during endocytosis. Dynamin's polymerization and activity are regulated by GTP binding and hydrolysis, with GTPase activity critical for membrane fission. Dynamin is also involved in other endocytic pathways and intracellular budding, and interacts with the cytoskeleton, particularly actin. In neurons, dynamin is essential for synaptic vesicle recycling, and mutations in dynamin 2 are linked to tissue-specific diseases, while mutations in dynamin 1 may contribute to epilepsy. Future research aims to elucidate the precise mechanism of dynamin-mediated membrane fission and explore its potential non-endocytic functions.Dynamin, a founding member of the dynamin-like GTPase (DLP) family, plays a critical role in endocytic membrane fission. Complementary approaches, including live cell imaging, cell-free studies, X-ray crystallography, and genetic studies in mice, have advanced our understanding of dynamin's mechanisms, essential roles in cell physiology, and the specific functions of different dynamin isoforms. Dynamin assembles into helical polymers at the necks of budding vesicles, promoting membrane fission through GTPase-dependent conformational changes. Three dynamin isoforms are expressed in mammals, each with distinct expression patterns and functions. Dynamin interacts with various proteins, including SH3-domain-containing proteins, and binds to phosphoinositides via its pleckstrin homology (PH) domain. The PRD region of dynamin interacts with SH3 domains to coordinate its function during endocytosis. Dynamin's polymerization and activity are regulated by GTP binding and hydrolysis, with GTPase activity critical for membrane fission. Dynamin is also involved in other endocytic pathways and intracellular budding, and interacts with the cytoskeleton, particularly actin. In neurons, dynamin is essential for synaptic vesicle recycling, and mutations in dynamin 2 are linked to tissue-specific diseases, while mutations in dynamin 1 may contribute to epilepsy. Future research aims to elucidate the precise mechanism of dynamin-mediated membrane fission and explore its potential non-endocytic functions.