Extracellular vesicles (EVs) have emerged as promising biomarkers for neurodegenerative disorders, offering unique insights into disease pathogenesis and progression. These vesicles, including exosomes, microvesicles, and apoptotic bodies, are small, membrane-bound particles released by cells that carry diverse molecular cargoes, including proteins, lipids, and nucleic acids. EVs are involved in intercellular communication and may facilitate spread of pathogenic proteins across the nervous system, potentially contributing to the progression of neurodegenerative disorders. Emerging evidence supports the ability of EVs isolated from biofluids such as blood, cerebrospinal fluid (CSF), and urine to reliably reflect the molecular signature of affected neural and other cell types, highlighting their importance as tools in noninvasive biomarker discovery. This chapter reviews the value of EVs as biomarkers in neurodegenerative disorders, explores their molecular composition, and discusses the latest advancements in EV isolation and characterization techniques. Furthermore, we examine the challenges and opportunities of EV-based diagnostics, emphasizing the potential of EVs as biomarkers for early detection and monitoring of Alzheimer disease (AD) and related dementias (ADRDs).