Anti-virus is a top tier software when it comes to the security of a computer, its purpose is to protect from viruses and malware software. If the system doesn’t have an anti-virus its basically inviting different types of viruses in. The anti-virus if set up correctly will be as a lock to a house, will not let anything suspicious come in, it also scans and checks software for any defects etc. If you don’t have an antivirus your system may:
Slow down
Lose data
Crash
It protects from spam and ads.
Prevents phishing attacks.
Firewall:
Having a firewall is as important as having a correctly set up anti-virus, not that many users have a firewall set up in their system. It prevents from anything that passes through the network into the system. It monitors the data coming through and the data going out into the network. The firewall inspects each packet that comes through for any hazardous threats. It also prevents from unwanted users that want to access the system.
Microsoft security, this is a very important aspect that has to be implemented from the start, this will allow the computer to receive new updates/patches directly from Microsoft, they can be sent for various reasons, to help the system by making it smother or fix a glitch that has been around for a while. No matter for what reason they sent you an update, You will have to keep the system up to date as some software may not even work with older versions of the system.