When we think of a Docker host, what comes to our mind? If you put it in terms of virtual machines that almost all of us are familiar with, let's take a look at how a typical VM host differs from a Docker host. A VM host is what the virtual machines actually run on top of. Typically, this is something like VMware ESXi if you are using VMware or Windows Server if you are using Hyper-V. Let's take a look at how they are as compared so that you can get a visual representation of the two, as shown in the following diagram:

The preceding image depicts the similarities between a VM host and Docker host. As stated previously, the host of any service is simply the system that the underlying virtual machines or containers in Docker run on top of. Therefore, a host is the operating system or service that contains and operates the underlying systems that you install and set up a service on, such as web servers, databases, and more.