If you've looked into hypervisors at all you have probably realized that there are a ton of different options and packages, even from one vendor there might be many different options like with Citrix and VMware. All of these can be separated into two groups. Type 1, commonly referred to as a bare-metal or client hypervisor. Or, Type 2, commonly referred to as a hosted hypervisor. Both of these are incredibly valuable, but your use case will greatly determine which you want to use.
Type 1 hypervisors are installed directly onto your system and are a standalone operating system, hence, bare-metal. Once you have installed this kind of hypervisor then you can install OSes onto the hypervisor and it will run that operating system once you spin it up to run. These systems you will typically be accessed by some remote connection or send actions via command prompt. You can have many virtual machines spun up on these kinds of hypervisors at once. Here is a list of type I hypervisors. Here are some type 1 hypervisors to look into(sorted by market share): ESXi , Hyper-V, and Xen.
Type 2 hypervisors, in contrast, do not run directly on the system and instead run inside of the host operating system. This means that if you are already running Windows Server 2016 then you might install a type 2 hypervisor into this environment. This is very handy if you need to run some linux only software or swap between operating systems. This will save you from needing to dual boot and do a restart everytime you want to go back and forth. These can be used in a similar way to how a type 1 is where you load up a few different operating systems and let it run in the background doing server tasks and that was common before everyone had virtualized their infrastructure because that allowed them to leave their current equipment and setup in place and simply take on additional functionality inside of a type 2 hypervisor, but at this point most people go directly for type 1 when they are building out their systems. Type 2 is mainly used now for individual systems needing another environment. Here is a list of type 2 hypervisors you might be interested in VMware Workstation, VirtualBox, QEMU