Grayware (or greyware) is a general term sometimes used as a classification for applications that behave in a manner that is annoying or undesirable, and yet less serious or troublesome than malware. Grayware encompasses spyware, adware, dialers, joke programs, lie detectors, barcode scanners, remote access tools, and any other unwelcome files and programs apart from viruses that are designed to harm the performance of computers on the user's network. The term has been in use since at least as early as September 2004.
Grayware refers to applications or files that are not classified as viruses or trojan programs, but can still negatively affect the performance of the computers on the user's network and introduce significant security risks to the user's organization. Often grayware performs a variety of undesired actions such as irritating users with pop-up windows, tracking user habits and unnecessarily exposing computer vulnerabilities to attack.
- Spyware is software that installs components on a computer for the purpose of recording Web surfing habits (primarily for marketing purposes). Spyware sends this information to its author or to other interested parties when the computer is online. Spyware often downloads with items identified as 'free downloads' or 'freeware' and does not notify the user of its existence or ask for permission to install the components. The information spyware components gather can include user keystrokes (keylogging), which means that private information such as login names, passwords, and credit card numbers are vulnerable to theft. Spyware gathers data, such as account user names, passwords, credit card numbers, and other confidential information, and transmits it to third parties.
- Adware is software that displays advertising banners on web browsers such as Internet Explorer and Mozilla Firefox. While not categorized as malware, many users consider adware invasive. Adware programs often create unwanted effects on a system, such as annoying pop-up ads and the general degradation in either network connection or system performance. Adware programs are typically installed as separate programs that are bundled with certain free software from sites like Download.com and Softonic. Many users inadvertently agree to installing adware by accepting the End User License Agreement (EULA) on the free software. Adware are also often installed in tandem with spyware programs. Both programs feed off each other's functionalities - spyware programs profile users' Internet behavior, while adware programs display targeted ads that correspond to the gathered user profile.