Hats off to HP for taking us to the basics needed by so many who operate computers. Hope this will continue and support your excellent brand. Feel a disclaimer is needed after that. I own no stock nor am I employed by HP or any of it's suppliers. I've just used the brand for a couple of decades.
It is a good basic article but it did ignore mention of how computers commonly get infected with malware. The primary vector is clicking on a link in email or on a web page. Many schemes are designed to take the user to a legitimate looking site and then entice them to click on a link that will cause malware to try to infect the users computer. NEVER click on a link unless you trust it.
Gets the points across to a novice! Yes, there maybe problems installing an antivirus software after a PC is infected though. Also, a lot of Rogue Antivirus software are on the Internet, hence one needs to be careful and get a genuine product.
