Learn in the textbookFundamentals and Types of Virtualization
DefinitionThe hosted type (ホスト型) installs virtualization software on the OS you normally use (the host OS) and runs virtual machines on top of it.
ExplanationYou can set it up much like adding one more application to an existing PC, so it is easy to try out. On the other hand, whenever a virtual machine uses the hardware, the work passes through the host OS, and that extra load (overhead) tends to slow processing down.
AnalogyIt is like a homeowner renting one room of the house they live in to a guest. The guest can use the room freely, but must go through the owner's home to reach the front door, kitchen, and bathroom.
Memory hookA host is the one who receives guests, and a guest is the visitor. The guest OS sits on top of the OS playing the host.