A web bug is a small piece of code that can be hidden in a transparent one pixel-by-one pixel image that is placed on a web page or in an HTML e-mail to monitor user behaviour. Unlike a cookie, a web bug is not easily controlled with internet browser settings.
A cookie is a small file that is put by a web site on a user's hard disk so that the site can remember something about that user at a later time.
According to Whatis.com, web bugs can be used to identify the IP address of the computer that fetched the web bug; the URL of the page that the web bug is located on; the URL of the web bug image; the time the web bug was viewed; the type of browser that fetched the web bug image; and a previously set cookie value.
Web bugs are mainly used by marketers for on-line traffic reporting, advertising, e-mail auditing and personalisation of web sites. They can be controlled by the web site operator or any other business that has been given permission to place them on a site – but not so easily controlled by the user.
According to the US-based NAI's guidelines, any use of web bugs requires notice. Such notice should disclose that web bugs are being used, the purpose of their use and whether data are transferred to third parties, through a link to the site's privacy policy.
The guidelines also provide that, when web bugs transfer "personally identifiable information" or sensitive information to third parties, web site operators must obtain the users' explicit consent for such transfers.
The guidelines create a distinction between third parties, companies that gather personally identifiable information through web bugs for their own purposes, and "agents", being companies that gather data only for the web site or marketer for which they are providing services.
The NAI said it has submitted its guidelines to the US Federal Trade Commission (FTC) for review. The group also said the guidelines will be used by TRUSTe, a coalition of companies including Microsoft Corp, AOL Time Warner and Intel, as a recommended best practice for its privacy seal programme.
The NAI guidelines are available from:
www.networkadvertising.org