• Adware, or advertising-supported software, is any software package that automatically renders advertisements in order to generate revenue for its author. The advertisements may be in the user interface of the software or on a screen presented to the user during the installation process. The functions may be designed to analyze which Internet sites the user visits and to present advertising pertinent to the types of goods or services featured there. The term is sometimes used to refer to software that displays unwanted advertisements.
  • Antivirus or anti-virus software (often abbreviated as AV), sometimes known as anti-malware software, is computer software used to prevent, detect and remove malicious software.
  • Browser hijacking is the modification of a web browser’s settings. The term “hijacking” is used as the changes are performed without the user’s permission. A browser hijacker may replace the existing home page, error page, or search page with its own. These are generally used to force hits to a particular website, increasing its advertising revenue.
  • A virus is a small infectious agent that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.
  • Malware, short for malicious software, is any software used to disrupt computer operation, gather sensitive information, or gain access to private computer systems. Malware is defined by its malicious intent, acting against the requirements of the computer user, and does not include software that causes unintentional harm due to some deficiency.
  • Potentially unwanted programs (PUP) is a software bundled, which can include software that displays intrusive advertising, or tracks the user’s internet usage to sell information to advertisers, injects its own advertising into web pages that a user looks at, or uses premium SMS services to rack up charges for the user.
  • Pop-up ads or pop-ups are often forms of online advertising on the World Wide Web intended to attract web traffic or capture email addresses. Pop-ups are generally new web browser windows to display advertisements.
  • Ransomware is a type of malware that restricts access to the system that it infects in some way, and demands a ransom paid to the operators of the malware for the restriction to be removed. Some forms of ransomware systematically encrypt files on the system’s hard drive (cryptoviral extortion, a threat originally envisioned by Adam Young and Moti Yung) using a large key that may be technologically infeasible to breach without paying the ransom, while some may simply lock the system and display messages intended to coax the user into paying.