Until the mid of the 1990s, when the Internet was only used by the US government and the major universities around the world, the only security threat that could harm home computer users were viruses. The latter used to spread via physical media (mainly floppy disks) and users needed only to install a good anti-virus which needed to be updated once or twice a year. The situation has changed a lot since then and nowadays (thanks to the widespread use of the Internet) we no longer hear about viruses, but security specialists speak about malware, a term which gathers under one umbrella a variety of unwanted software such as viruses, worms, root kits and spyware. In this article the difference between the last term and adware will be exposed because these terms refer to indeed different things, even though a lot of confusion exists among home users as to what the actual difference entails.
Adware
Even though adware attracts its share of negative connotations in the mind of most people, actually it is not something illegal. The basic idea behind adware is that of using fully functional software without paying for it. In return the end user should accept to ‘look at’ advertisements. This is similar to watching TV, where usually a programme is interrupted for some minutes to show adverts. In the case of adware, the software does not stop to show adverts (as in the case of TV) but usually the user sees an advert all of the time in a banner (which occupies a part of the software window). In the meantime, the user can continue to work with the application and he or she can totally ignore the advert. When this model is adopted, the software developer can release ‘free’ software because revenue is generated from the advertisements rather than directly from the users who in the traditional software model would purchase the application. Examples of adware are AOL Instant Messenger, DivX, Gator, Messenger Plus! Live, WinAce, Windows Live Messenger and Yahoo! Messenger. For an application to be classified as adware, the user has to be informed about the advertisements during the installation. However, it is a fact that most users do not read any information during the installation process and just keep on clicking on ‘Next’ until the final ‘Finish’. Some of these users are usually surprised to see the advertisements when they launch the application and suspect that the program should be classified as malware!
Spyware
Whereas adware is technically legal, the same cannot be said of spyware. Spyware can take various forms and like adware can also show advertisements (even though this is not always the case). An application is classified as spyware when on the foreground (what the user sees) it offers something useful and visible to the user, whereas on the background (what the user does not see) it is collecting information like keystrokes and browsing habits, and these are sent to some server for data mining, without the knowledge of the end user! Examples of spyware are CoolWebSearch and MyWebSearch. When the first spyware appeared on the Internet, it could be easily removed manually. However, lately spyware developers are using advanced techniques where manual removal is virtually impossible (unless attempted by security experts) and where in certain circumstances even automatic removal (with the aid of specialised applications) is very difficult.
The above is indeed a brief introduction to the topic of adware and spyware, and without doubt much more can be written. Nevertheless, this article should help most home users understand the difference between the two terms.