What is a Virus?
A computer virus is a form of malicious software that attaches itself to legitimate files and applications, with the intent to cause damage or disruption. It can infect systems by taking advantage of security vulnerabilities in programs or networks, allowing it to spread quickly from one system to another. Viruses may be programmed to delete files, corrupt data, steal sensitive information, display messages or even take control of an entire system. They often rely on social engineering techniques to trick unsuspecting users into downloading and running them. The best way to protect a system from viruses is through regular maintenance, keeping all software up-to-date and using reliable anti-virus protection.
Computer viruses work by attaching themselves to existing files and applications, known as hosts, in order to gain access to the system. The virus then replicates itself and spreads throughout the system, accessing additional files and programs. It can also propagate across networks, using file-sharing protocols or email messages with malicious content — such as an infected attachment or a link leading to a malicious website — to reach its target. Once on the system, it may be programmed to perform any number of malicious actions such as deleting data, corrupting files, stealing confidential information or taking control of the entire system. In addition, many computer viruses can spread not only from computer to computer but also from device to device — for example from smartphones to PCs or tablets.
In some cases, viruses may even be programmed to remain idle until triggered by a certain event or condition, such as the passing of a certain date or the presence of specific files on the system. This is known as “trigger-based” malicious code and can make it difficult to detect and remove.
The best way to protect against computer viruses is through regular maintenance — keeping all software up-to-date, using reliable anti-virus protection and taking other security measures such as restricting user access rights — in order to reduce the risk of infection. It is also important to be aware of potential risks when downloading files from unreliable sources or opening suspicious email attachments. By taking these preventive steps, users can help protect their systems from malicious viruses.
It is important to keep in mind that even when a virus has been removed, there may still be residual damage or disruption caused by the infection. Therefore, it is essential to check that all programs and data are functioning correctly after a virus attack and to update any security measures as necessary.
Simplified Example
A computer virus is like a bad cold that you can catch from other people. Just like a cold can make you feel sick and can spread to other people if you're not careful, a computer virus is a type of software that can harm your computer and can spread to other computers if you're not careful. It can slow down your computer or even destroy important files, just like a cold can make you feel bad and stop you from doing things you want to do.
Who Invented the Virus?
Dutch microbiologist Martinus Beijerinck is credited with coining the term "virus" in 1898. During his research on a disease affecting tobacco plants, Beijerinck identified a filterable agent smaller than bacteria as the cause of the ailment. He named this novel agent a "virus," drawing from the Latin words "poison" or "toxin."
Examples
WannaCry: WannaCry is a type of ransomware that spread rapidly across the world in May 2017. The virus infected computers running Microsoft Windows and encrypted users' files, demanding a ransom payment in exchange for the decryption key. WannaCry caused widespread disruption, affecting organizations in more than 150 countries and causing millions of dollars in damages.
ILOVEYOU: ILOVEYOU is a computer virus that was first released in May 2000 and quickly spread across the world, infecting millions of computers. The virus was a type of worm that was sent as an email attachment and, when opened, it would replicate itself and send itself to all of the contacts in the infected user's address book. ILOVEYOU caused widespread damage, overwriting files and disrupting businesses and individuals alike.
Conficker: Conficker is a computer worm that was first discovered in 2008 and quickly spread to millions of computers. The virus was designed to exploit a vulnerability in the Microsoft Windows operating system and was used to steal sensitive information, such as passwords and financial data. Conficker was particularly dangerous because it was able to spread rapidly across networks and infect a large number of computers, making it difficult to control and remove. Despite being discovered more than a decade ago, Conficker continues to be a threat and is still present on many computers today.