The VMware software stack consists of three layers: virtualization, management, and interface. The relationship between these layers is shown in the following figure:

The virtualization layer of VMware vSphere consists of infrastructure services and application services. Infrastructure services abstract, aggregate, and allocate all hardware and other resources. Infrastructure services include:

Application services are designed to ensure availability, security, and scalability for applications; for example, features such as vSphere High Availability and Fault Tolerance.

The management layer is represented by VMware vCenter Server, which is the main central point for configuring, provisioning, and managing your virtual environment.

The interface layer is where user access to vSphere happens. Users can access the environment using GUI clients such as vSphere Client or vSphere Web Client. Also, users can access the datacenter using command-line interfaces or SDKs for automated management or third-party product connections.