A computer virus is a malicious software program designed to replicate and spread between devices. While many use "virus" as a general term for all malware, a true virus can infect multiple systems by attaching itself to files and programs.

The first recorded computer virus was created in 1986 by two software developers aiming to prevent piracy. However, most modern viruses serve more harmful purposes, such as stealing sensitive data, corrupting files, or disrupting system functionality. Some may even display nuisance messages while spreading further.

Malware, short for malicious software, is a broad term for any software designed to harm or exploit a computer, network, or user. It includes viruses, spyware, ransomware, trojans, and other harmful programs.

Malware can slow down systems, steal information, or allow hackers to control devices remotely.

Spyware is software designed to secretly monitor user activities, often to steal personal information. It can log keystrokes, track browsing habits, and even collect banking details.

Many forms of spyware come bundled with seemingly legitimate programs, such as free browser toolbars. Users can avoid most spyware infections by carefully reviewing installation agreements before downloading software.

Adware is a type of malware that displays intrusive advertisements based on your browsing habits. It typically comes bundled with free software, installing itself without the user’s clear consent.

While some adware is relatively harmless, excessive ads can slow down your computer, compromise security, and redirect you to unsafe websites.

Phishing is a cyber-attack where criminals send emails or messages pretending to be from trusted organizations like banks, PayPal, or social media platforms. These emails typically urge users to click a link and enter personal details on a fake website designed to look authentic.

By entering their information, users unknowingly provide hackers with login credentials, financial details, and other sensitive data, allowing criminals to commit fraud or identity theft.

A worm is a self-replicating program designed to spread across networks without the need for a host file. Unlike viruses, worms don’t require user interaction to propagate; they exploit vulnerabilities in operating systems and software.

Worms often carry payloads, such as additional malware, ransomware, or spam bots. They can also be used to create zombie networks (botnets), where thousands of infected computers are controlled remotely to launch cyber-attacks.

Ransomware is one of the most dangerous types of malware. Once installed, it locks or encrypts the victim’s files and demands payment for their release. Often disguised as legitimate software, ransomware can spread through infected email attachments, malicious downloads, or compromised websites.

Recent ransomware attacks have affected thousands of users, with cybercriminals impersonating antivirus programs and tricking people into paying to "remove" non-existent threats—while also stealing their payment information.

A rootkit is an advanced form of malware designed to hide its presence from the operating system. It often allows hackers to maintain remote access and control over a compromised device while avoiding detection.

Because rootkits modify core system processes, they are incredibly difficult to detect and remove.

Specialised tools are often required to eliminate them without causing further system damage.

A keylogger is a type of spyware that records every keystroke made on a computer. Cybercriminals use keyloggers to steal usernames, passwords, credit card details, and other sensitive information.

Keyloggers can be installed through malware infections, malicious email attachments, or compromised software downloads. They pose a severe risk to personal and financial security, as they can silently capture login credentials and banking details without the user knowing.

A trojan, or Trojan horse, disguises itself as legitimate software but contains hidden malicious code. Users may download a trojan believing it to be a useful program, only for it to open a backdoor, allowing hackers to gain control of their device remotely.

Trojans are commonly used to steal sensitive information, install further malware, or turn infected computers into part of a botnet used for large-scale attacks.

While cyber threats are constantly evolving, following best practices can help keep your system safe: