I've written on this topic before, but given the popularity of Solus, and the many forum messages about problems with dual-booting schems (mostly Windows + Solus), I've decided to list again some of the many advantages of this alternative method. Let me start out by making it clear - as always - that I'm not trying to change anybody's mind about anything. I'm just presenting another way to have both Windows and Solus sharing your machine. It's a way that totally avoids all the pitfalls of common dual-boot schemes.

What Are Virtual Machines?
They're simply software - an application - that runs a second operating system as a "guest" of your computer - which is called the "host." In that sense, a VM is like a browser, or a word processor. It can be created by a VM manager such as VirtualBox, and removed if you ever decide you don't need it anymore. The host machine shares some of its abilities with the guest, such as a network and peripheral devices, and the VM software provides everything else that's needed for the VM to operate.

What's required to use them?
A virtual machine manager, such as VirtualBox (in the Solus repo) is needed to create a VM. In fact, it can create many different VMs, in case you'd like to try out other interesting Linux distributions without replacing your primary operating system. If your host machine is robust enough, you can even run more than one VM at a time (although performance will suffer a bit). The most common use of a VM that's discussed here is one that allows you to use both Windows and Solus without a complex and trouble-prone dual-boot scheme.

Which OS should be virtualized?
Since a small amount of performance is lost on the host machine when running a VM, most folks install the virtual machine manager on the physical system that's most important to them. VirtualBox, for example, operates identically on Linux or Windows, so if you spend most of your time on Windows, you would install VirtualBox there, and create a VM to run Solus. However, as in my case, if Solus is the more important system to you, and Windows is rarely needed, then you should install VirtualBox on Solus and create a VM to run Windows.

Multiple systems are possible.
As I suggested above, you might be interested in "distro hopping," or examining other distros you're curious about, and it's important to know that you can create multiple VMs, not just one. Right now, for example, I have on my main laptop four Solus VMs - one each for Budgie, GNOME, Plasma, and Xfce - plus one for Windows. I can use the Solus VMs to help me answer questions in the forum, and the Windows VM if I ever need to run a program that's not availabe as a Linux version. In fact, I can use the screen capture utility on my laptop to create images from the Solus VM that's using the desktop environment we're discussing. If you ever decide that a particular VM isn't needed anymore, you can simply remove it using the VM manager. It's as simple as deleting a file that you're no longer interested in keeping.

Concurrent operation.
Unlike a dual-boot scheme, which requires you to shut down one system in order to use the other one, it should be clear by now that both the host system and the guest system run at the same time. With VirtualBox, for example, you can put a shortcut to a VM on your desktop, and launch it with just a single mouse click. So if you're working on the host system, and need a quick look at the guest system - say, to check on email there, or to copy a link from the browser there - you don't need to shut down your host machine to do that. They're both available concurrently.

Obtaining the guest operating system.
With any of the VM managers, you'll need a copy of the guest system's installation file, the .ISO file that's available from the system's web site. So to install Windows on a VM, you can get the needed file from windows.com. Or to install a different Linux distribution, look on that distro's web site for a Downloads section, or perhaps look on DistroWatch for that.

How to install VirtualBox.
Is VirtualBox the only option for creating virtual machines? No, it's not. There are other programs that you'll see mentioned in the forum, such as GNOME-boxes, and virt-manager (both available in the Solus repo) that can be used to create and run VMs. I've tried those and VirtualBox is the one that gives me all the features I need and is easy to use. Others, with fewer requirements, may be perfectly happy with one of the alternative systems.

To install VirtualBox on Windows, just point your browser at virtualbox.com, and download the program from there, like any other third-party Windows application. On Solus, you can find it using Discover or the GNOME equivalent, or you can install it using the terminal. The command to use there differs depending on which kernel your system uses. If you're using the LTS (long-term support) kernel, the command to install VirtualBox is sudo eopkg it -y virtualbox. On the other hand, if you're using the current kernel, the command to use is instead sudo eopkg -y virtualbox-current.

The VM manager can then be found in the Solus "System" menu as "Oracle VirtualBox." It includes a very complete help system, so most usage questions can be quickly resolved there, or just ask here in the forum. Many users here are able and happy to help you if you run into problems.

If you prefer to dive right in and create a VM, just go to the Machine menu in VirtualBox and click on New. That will allow you to create the two files that actually constitute a VM - one that contains settings, and one that's the virtual hard drive of the VM.

Conclusion.
I hope I have made it clear what a VM is, and one way you can create and use them. I'll say once again that I'm not trying to change anyone's mind, if you're happy with your dual-boot scheme, but there does exist a better alternative in my opinion. If I've raised other questions in your mind, feel free to ask me here.

Thank you very much for this detailed information Wetgeek.
It is much apreciated.
Since i don`t use window much anymore this could be the way to go.

If i will ever get this to work i could use the 2 TB NVME for Solus.

Keep in mind that Solus' resource requirements are very modest. I create my Solus VMs with a virtual hard drive size of 32 GB. That even allows for a swap partition that's big enough for hibernation.

I do my heavy data lifting with a NAS (network attached storage) server, so my VMs don't need a lot of memory beyond the operating system itself. So you use a NAS, or "cloud" storage, you could fit a LOT of VMs into your 2 TB SSD. If you only need one VM, you'll have room for a lot of personal data, like documents, videos, pictures, etc.

Personal choice. I would always try to make the host OS the one with the lowest system load. Therefore Solus as host, Windows as VM.
If you run Windows as host then much of the performance of Linux is soaked up by Windows resource sucking.
Solus is also my preferred OS so it works out well for me.

    BuzzPCSOS I would always try to make the host OS the one with the lowest system load.

    I make that decision differently, as I've mentioned, but the result comes out the same as yours. I use Solus as the host, because that's my daily driver, and Windows is something I rarely have any need for. We may have different criteria, but in the end, the outcome is the same.

      I installed win 10 in VirtualBox in the morning.
      But since i switched to fullscreen i have no mouse anymore.
      I have no chance to configure anything in win.
      Any ideas ?

        MikeK61 For your mouse (and other stuff) to work reliably you need to install VBoxGuestAdditions_7.1.2.iso onto the guest OS.
        Do this by clicking on the menu at the top, select Devices and use the 'Insert Guest additions CD Image' dialogue. Alternatively it can be downloaded from here and mounted as a CD image (again using the Devices menu) and run as a CD.
        Right Ctrl C should get you out of full screen and able to use your mouse again.
        Make sure you have added yourself to the vbox users group with sudo usermod -aG vboxusers $USER
        A reboot and everything should be working.
        Edit: There seem to be some issues using full screen and a mouse on the current version.
        Right Ctrl+F Fullscreen
        Right Ctrl+C Scaled mode
        You can generally manoeuvre round Windows without a mouse using Tab, Space bar and arrow buttons.

          Seems to work Thanks much.
          A few things bothering me.
          Display settings are sub optimal.
          I can only choose lower settings than on the host.
          Also i have no access to local hard drives.
          Is there a chance to share at least one drive so i can share some files ?

            MikeK61 i have no mouse anymore

            Sorry, I'd like to help, but I've never seen that happen. How is the mouse connected? Bluetooth, wired, or wi-fi? Knowing that might help someone to suggest what to do about it.

            If it's Bluetooth or wi-fi, do you also happen to have a wired mouse you could try, just to help diagnose the problem? (I keep one of those on hand to help with installing a system, before Bluetooth becomes available.)

              MikeK61 VMs are a bit of a steep learning curve. Best to write some of it down for the next time.
              Under the Devices menu there will be Shared Folders. For safety and security it is better to share as little with the Host as possible. I usually set aside one folder for sharing on the Host and copy everything I need there. Use Shared Folders to navigate and select your chosen folder.
              I seem to remember there are a lot of settings that can be tweaked with for display optimisation from the VirtualBox settings page. At this point it is probably best to export your VM to a single file just in case the whole lot gets messed up while you are learning. That way you have a datum that can be reinstalled on any machine running VirtualBox.
              VirtualBox makes a good second OS alternative for things that can't be done on your primary OS. For best results don't expect to play games, music or run any graphic intensive programs. All your resources are being shared with the host and will always take a performance hit because of that. You are also dependant on the power of the software to make a good job of the resource sharing. Sometimes an update will make things better, sometimes not.

                MikeK61 Also i have no access to local hard drives.

                In order to access my NAS from a VM, I need to use the Network setting "Bridged Adapter." That way it shares a connection on the host that already has access to the local network, instead of a virtual network. That's probably what you need for accessing local drives, too. That's trivial to do with VirtualBox (one mouse click), but a real pain with other virtualization schemes - one of the reasons I like VBox so much.

                  5 days later

                  I have installed win 10 on VirtualBox and it works.
                  Can i use USB for example. ?
                  To share a drive i need to change permission for the drive but always get an error permission denied.

                    MikeK61 Can i use USB for example. ?

                    Click on the "Devices" menu item. If it's correctly set up, you can access whatever's at a USB port by selecting it there. You can also use that menu to connect with any of the other devices that are enabled in the settings (shared folders, etc., etc.).

                      Thanks much Wetgeek i`ll try that.
                      Tomorrow i have to get rid of the water in my lungs in the hospital first.
                      Not sure how long i have to stay.

                        4 days later

                        MikeK61 Hope you are back and fighting fit soon.
                        While setting up VirtualBox it is probably better to stay out of full screen (ctrl + c) and use the program controls at the top of the screen. Also check the Vbox status indicators and controls in the lower right hand corner of the program window.
                        Mostly when sharing stuff you will not be allowed access by both the host and VM at the same time. A USB can only be made available if it is not being used by the host. Setting the USB to selected in the devices menu makes that selection for you.
                        Sometimes watching online videos and seeing how others are making things work can be really helpful and much quicker than reading a ton of instructions.

                            BuzzPCSOS While setting up VirtualBox it is probably better to stay out of full screen (ctrl + c)

                            By the way, unless I misunderstand what you're suggesting, it's RIGHT CTRL+F to toggle full-screen. That can be changed in the settings for the VBox manager application, but I've never found a reason to change it.

                            BuzzPCSOS Sometimes watching online videos and seeing how others are making things work can be really helpful and much quicker than reading a ton of instructions.

                            Indeed, it can. And the last time I looked, the VBox help file was 250+ pages. (I printed a copy of that once, when I was a new user.) It's well indexed, in the manner of professional documentation, because VirtualBox is used by enterprises that pay a lot to license it. I love that the full-featured version has always been available for free for personal use.

                                  WetGeek Thanks for your correction but I was rather clumsily trying to indicate how to exit full screen not enter it. Just wanting to get the information across without looking at how easily understood it would be 🙂
                                  As for written instructions tldr is the norm.

                                      BuzzPCSOS I was rather clumsily trying to indicate how to exit full screen not enter it.

                                      If your "ctrl+c" refers to the right ctrl key (the default HOST key), then CTRL+C indeed removes a VM from full-screen mode (or even windowed mode). It changes the VM to scaled mode, which is interesting, but not the same as just exiting fulll-screen, and it doesn't have the menu at the top or the status symbols at the bottom.

                                      Pressing ctrl-c on a full-screen VM using the left CTRL key does nothing at all, in my experience, unless you've previously bound that keypress to a command. I was just pointing out that CTRL+F is the default toggle that enters and exits full-screen mode. Not sure why you would use one command to enter it, and another to exit it, but if that works for you, I'm all for it.

                                      Regarding tl;dr, I agree with you that it's often true of amateur help files. I find that the indexing in the professionally-created VBox help system makes it easy to jump right to the topic of interest, often just one paragraph or two. It's also available via a keypress right from the VBox manager, so no searching for a video is needed. If you've never used it, it's worth taking a look.

                                      Not trying to start a debate, just pointing that out for the benefit of other readers who might be new to VirtualBox.

                                          WetGeek Wow, yes. My bad. I meant to edit my post to right ctrl +C, but other commitments got in the way. It should have been something else anyway.

                                          WetGeek Not sure why you would use one command to enter it, and another to exit it

                                          😆 Well I live and learn, must spend more time watching video tutorials. The idea of using the same key combination to enter or exit a command never occurred to me, it's like enter and exit meaning the same thing. Thank you for your correction.

                                                BuzzPCSOS it's like enter and exit meaning the same thing

                                                No worries! Again, not meaning to debate this, but I think you'll find HOST+F very useful and intuitive.

                                                If your VM is IN full-screen mode, then HOST+F exits from that mode (it can't enter it, because it's already there). If it's NOT IN full-screen mode, then that keypress causes it to enter it (it can't exit, because it's already ... well, you get the idea).

                                                Toggles are a very common way to turn things on and off via software. Context is your friend.