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A computer virus is malware that can spread and multiply independently via host programs. This is why the name "virus" was chosen for this type of malware, because the biological counterpart also works in the same way. The digital viruses are not only limited to computers with Windows, Linux and macOS, but can also theoretically infect Android, iOS and other operating systems. Servers with their own systems can also be attacked and damaged by viruses. The type of damage that is done is not specified. When naming malware as a computer virus, the focus is on how it is spread. See below for more details.
A computer virus, like pretty much any other software, has to be written by someone. In addition to the harmful factors of the program or script, this person then also creates the elements that allow the virus to infiltrate systems and programs and spread through them. For example, an e-mail virus can get onto the computer through an attachment, settle in the e-mail client (Thunderbird, Outlook, Mail, etc.) and thus spread with every e-mail you send. Alternatively, it can be in the Browser (Edge, Firefox, Chrome, Opera, Safari, etc.) to nest or infect other programs.
In short, one person writes the virus and spreads it, then it spreads on its own through other host apps. In addition to e-mails, this can also happen through downloads - program downloads from dubious sources, archives with self-starting apps, documents, graphics or videos with hidden elements, and so on. Viruses do not appear in their pure form, i.e. as a mere script or individual app. They are embedded in (or copy themselves into) a host program that, when run, releases the virus. They then use the computer as a living space and look for points of attack there. Modern systems usually know how to prevent this.
In addition to the file virus that has been primarily described up to this point, there are also other types of computer viruses. Here is a small overview of the classification:
As already mentioned, the designation of a computer virus is not limited to its influence on software and hardware. The term "virus" only indicates that the malware spreads independently. Therefore, the damage done by a virus to a computer can vary depending on the specific type. Here some examples:
According to developers and advertising departments of antivirus software, there is nothing worse in the world than a computer virus. However, this type of malware lost its relevance around 15 years ago. Because the most common distribution channels are now protected and existing points of attack only affect niches. Ergo, there is hardly any danger from real computer viruses for private users. They were made by worms Trojans, rootkits, spyware, ransomware, and other more specific software that spread differently.
While viruses are often intended to annoy and/or cause damage, malware, which is now more common, has specific purposes (spying, collecting data or encrypting it for blackmail, taking over computers, etc.). Modern antivirus software should also recognize and block most of these attacks and remove the causative software. However, it will not be renamed, probably due to the marketing based on the name and the lay target group. The benefit of these protection programs is a topic of its own - of course there are pros and cons. But more on that elsewhere.
Nowadays it is actually enough to sit down at the computer with your eyes wide open and not be tempted by (sometimes really obvious) lure maneuvers to access dubious sites or downloads from dubious sources when using the Internet. E-mails should also be checked for the sender. If the person or company seems unknown, then the mail should be deleted. Links and attachments should only be opened with special care. The greatest danger here is now phishing (Guide: How to recognize phishing emails). Virus scanners and antivirus apps promise a lot, but are often superfluous. Due to the required system access, they can also serve as a gateway themselves.
I have tried to give you a comprehensive insight into the topic of "computer viruses" with this post here on the Sir Apfelot Blog. Of course, I couldn't squeeze all the information into the present framework. So here are a few more sources that can help you with further research:
After graduating from high school, Johannes completed an apprenticeship as a business assistant specializing in foreign languages. But then he decided to research and write, which resulted in his independence. For several years he has been working for Sir Apfelot, among others. His articles include product introductions, news, manuals, video games, consoles, and more. He follows Apple keynotes live via stream.