VHDX is a file format used by Microsoft Hyper-V to store virtual hard disk drives. It allows users to create, manage, and store virtual machines on a physical server. VHDX files can hold operating systems, applications, and data, making them essential for virtualization. One of the key features of VHDX is its support for larger disk sizes, up to 64 terabytes, which is significantly more than its predecessor, VHD. Additionally, VHDX files offer improved performance and resilience against power failures, making them a reliable choice for enterprise environments.