How do you protect your computer from a virus without anti-virus software?

Here is what I found. I am also a common man and not a software guy. I protect my system with deepfreeze.

Deep Freeze, by Faronics, is a software application available for the Microsoft Windows, and macOS operating systems which allows system administrators to protect the core operating system and configuration files on a workstation or server by restoring a computer back to the saved configuration, each time the computer is restarted. (From Wiki just to show you what it is all about).

IMPORTANT - firstly understand what the software does.

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Deep Freeze is a kernel-level driver that protects hard drive integrity by redirecting information being written to the hard drive or partition, leaving the original data intact. This redirected information is no longer referenced once the computer is restarted, thus restoring the system to its original state at the disk sector level. This allows users to make 'virtual' changes to the system, giving them the appearance that they can modify core files or even delete them, and even make the system unusable to themselves, but upon reboot the originally configured 'frozen' state of the operating system is restored.

[citation needed]

To make changes, a system administrator must 'thaw' the protected partition by disabling Deep Freeze, make any needed changes, and then 'freeze' it again by re-enabling Deep Freeze. These changes become part of the protected partition and will be maintained after restarts. 'Freezing' and 'thawing' can be done at the workstation level or remotely via either the Faronics Core management platform or the Deep Freeze Enterprise Console. Users of the Enterprise version can also create virtual partitions called ThawSpaces (of up to 1 TB on an NTFS-formatted drive) to retain data on "frozen" hard drives after restarts.

>> Also you can read: Is there really best or better antivirus

Deep Freeze can also protect a computer from harmful malware, since it automatically deletes (or rather, no longer "sees") downloaded files when the computer is restarted. The advantage of using Deep Freeze is that it uses very few system resources, and thus does not slow down computer performance greatly. The disadvantage is that it does not provide real-time protection, therefore an infected computer would have to be restarted in order to remove malware.

So in layman terms.

1. Computer with fresh installed windows and all necessary software - ready to go.
2. INSTALL the deepfreeze software. (System will reboot after installation).
3. Give a password of your choice. ENJOY.
4. Tips - Make sure during installation C drive is selected to be frozen. You will have C, D, E… so on. Leave out any other drive such as D drive or E drive to save your daily routine stuff so that it does not delete at next boot.
5. If you require some extra software that you need to be installed, you will have to manually give PERMISSION by going to THAW mode. I will show you how…
6. The deepfreeze icon will be near your system clock) - you have to keep pressing shift and double click the deepfreeze icon).
7. A window will pop up where it will require your password. Once you enter password, you can select boot THAW and APPLY AND REBOOT system now.
8. Now C drive is ready to accept new software. Install what you want. Do steps by clicking deepfreeze icon and FREEZE it. System will reboot and you will have your new software.
9. Note - nothing else will be saved in C drive. If your new software does some changes to anything in C drive, it will be erased at next boot. So if the newly installed software saves something by default in C, then during installation process, change that default software save path to your unfrozen drives example - D.

ALL THE BEST.