What is a Virtual Machine
VMware Player is a program which emulates hardware with a system UEFI/BIOS that is suitable for the OS being installed in question. This allows one to install another Operating System, the guest Operating System which acts as a window within the host PC. Because the hardware is virtualised to be suitable to the guest OS in question, it can also be used to install a legacy operating system which has no driver support for newer hardware.
This is incredibly powerful when one wants to run software that is only compatible with a Legacy Version of Windows or another type of Operating System. For example a scanner with drivers and software for Windows XP may be ran on a Windows XP Virtual Machine that runs on a Windows 10 Host.
VMware Workstation Player
VMware player can be downloaded from VMware using the following link. For VMware to run smoothly it is recommended to have a PC that has at least a 6th generation Intel i5 Processor, 8 GB of DDR4 RAM and a 250 GB SSD (with 100 GB of free space).
Microsoft Windows 90 Day Trial Test Virtual Machines
Microsoft have made a number of Virtual Machines available to download with different versions of Internet Explorer. These Virtual Machines are designed for short term software testing and will expire after 90 days at which point you can start with a new virtual machine.
A Virtual Machine is a great way to try Linux without ruining your Windows Install. One of the best Linux distributions to get started with for Windows users is Linux Mint. Another popular distribution is Ubuntu.
Legacy End of Life Windows
Windows 7 Pro
For Windows 7 Pro you can either perform a clean install and activate using OEM Downgrade rights from a Windows 10 Pro Host PC for product activation by porting the SLIC 2.1 across. Or alternatively use VMware vCenter Converter to create a Virtual Machine image of the physical machine and activate using OEM Downgrade rights from a Windows 10 Pro Host PC for product activation by porting the SLIC 2.1 across.
Windows XP Pro
Unfortunately the popular Operating System Windows XP is not yet abandonware and the website WinWorld cannot host the Windows XP Installation ISOs. I suspect it'll be at least another 10 years until Microsoft allow them to upload the ISO for this OS. However as a workaround we can download Windows XP Mode and convert it to a Virtual Machine for use in VMware Player. There is an official activation mechanism for this but it will only work on a Windows 7 Pro, Windows 7 Ultimate or Windows 7 Enterprise Host and not of Windows 10 Pro (despite it being a free upgrade from Windows 7 Pro). The install however does generate a New Installation ID and its possible you can use this for Phone Activation.
There is a Linux Distribution ReactOS being developed which attempts to emulate Windows XP. It is still in the Alpha stage and VMware Tools don't work correctly on it.
The website WinWorld hosts installation ISOs and Product Keys for Windows versions which are over 20 years old. These can be installed in VMware Workstation Player. I have wrote a guide for Windows 98SE and some additional notes as I needed Windows 98SE to revive an old scientific instrument when I worked at a University.
Converting CD/DVDs into ISO Images and Floppy Disks into FLP Images
In many cases you may need to convert physical media to file that can be copied over to your Windows 10 Host PC and loaded as a Virtual CD/DVD or Virtual Floppy Drive. Use WinImage for CDs and Floppy Drives. I think the free version has an upper size limit so use ImgBurn for DVDs (note some Security Products such as Malwarebytes Antimalware dislike ImgBurn as its installer included an optional toolbar).