Nanocrystals are defined as materials comprising atoms arranged in single crystals or polycrystalline structures with dimensions below 100 nm. These nanoscale systems offer unique benefits compared to conventional therapeutic preparation, including high bioavailability, improved targeting selectivity, and controlled drug release, making them highly valuable in drug delivery applications. Their distinct physical and chemical characteristics enable the efficient delivery of diverse therapeutic agents, including genetic materials, anticancer drugs, and poorly water-soluble compounds, offering a broad spectrum of potential applications. Advancements in nanocrystal technology have continuously refined their development, leading to several promising formulations reaching clinical evaluation. Despite these advancements, challenges such as safety concerns and stability issues persist, emphasizing the need for further research in this area. This book chapter outlines a detailed exploration of recent progress in the field of nanocrystals, focusing on novel preparation strategies Intended to enhance the bioavailability of poorly soluble drugs, critical physicochemical properties, advanced characterization methodologies, and innovations in drug administration routes. Additionally, the chapter explores the therapeutic potential of nanocrystals in various pharmaceutical applications, aiming to highlight their transformative role in modern drug delivery systems.