Windows Server is a group of server operating systems developed by Microsoft. It is designed to manage network resources, provide services to users, and support applications in a business environment. Windows Server offers features like file storage, security management, and virtualization, making it suitable for organizations of all sizes. The operating system comes in various editions, each tailored for different needs, such as Windows Server Essentials for small businesses and Windows Server Datacenter for large enterprises. Administrators can use tools like Active Directory to manage user accounts and permissions, ensuring a secure and efficient network environment.