A computer virus is malware that attaches itself to programs or files and spreads when they are run.
Viruses can damage data, slow down systems or download further malware.
Types of Computer Viruses
Viruses differ in where they hide and when they become active.
Boot Sector Viruses
Boot sector viruses infect the start area of hard drives or storage media.
They load during start-up, before the operating system and many protection programs are running.
Direct Action Viruses
Direct action viruses become active when the infected file is run.
They then infect other files in the same folder or in certain locations and terminate again.
How Computer Viruses Spread
A virus needs a carrier and an action by the user, such as opening a file.
Through Email Attachments
Infected attachments pose as invoices, job applications or delivery notes.
Opening the file or enabling macros starts the virus.
Through Downloads and Infected Websites
Cracked software, fake updates and manipulated download sites often contain viruses.
Infected USB sticks and network drives also spread malicious code.
Prevention and Removal of Computer Viruses
Several simple measures together provide good protection.
Using Antivirus Software
Up-to-date antivirus software detects known viruses and suspicious behaviour.
Regular updates of the operating system and programs close the gaps that viruses use.
Being Careful with Email Attachments and Downloads
Only open attachments you expect, do not enable macros from unknown sources and download software only from the maker’s website.
Backing Up Your Data
Regular backups on separate storage allow recovery after an infection.
Backups should be kept offline or write-protected.
Conclusion
Computer viruses are one of the oldest threats but remain relevant.
Updated systems, care with files and good backups keep the damage small.