What Is Adware?

Adware, a term derived from "advertising-supported software," is software that displays advertising on a computer screen or mobile device, redirects search results to advertising websites, and collects user data for marketing purposes.

Adware's purpose is to generate revenue by serving ads to an Internet user while they are surfing the web or during the initial installation of programs or applications such as toolbars or games. Adware can take a variety of forms from display and banner ads to full-screen ads, videos, and pop-ups.

Most adware is legitimate and safe to use, but some can be malicious in nature. Users can often disable the frequency of adware or what kinds of downloads they allow by managing the pop-up controls and preferences within their Internet browsers. 

Key Takeaways

  • Adware is an "advertising-supported software" that displays ads on websites and collects data on a user's behavior for marketing purposes.
  • Adware generates revenue for a company through display and pay-per-click advertising.
  • Not all adware is malware.
  • Antivirus software is essential to help protect a computer and its user from malicious adware.

How Adware Works

Adware, which works well with most web browsers, can track which Internet sites a user visits and then present advertisements based on the types of webpages viewed. Adware, while sometimes intrusive and annoying, is usually not a threat to a computer system. It is hardly ever noticed by computer users, rarely making its presence known.

Generally speaking, adware generates revenue in two ways: the display of advertising to a user, and a pay-per-click payment made if a user clicks on the ad.

Adware History

When adware use began, roughly in 1995, some industry experts considered all adware to be spyware, which is software that enables someone to collect covert information from a user's computer without the user's knowledge. Later, as the legitimacy of adware grew, it was thought of as merely a "potentially unwanted program."

As such, its use proliferated and not too much was done to monitor its legitimacy. It wasn't until the peak adware years of 2005–2008 when adware vendors started to monitor and shut down questionable activities.

Adware and Malicious Use

Adware is considered by many to be synonymous with malware, which is malicious software intended to cause damage to a computer or network. Types of malware include viruses, worms, spyware, and adware. Malicious adware can find its way onto computers through pop-up ads, unclosable windows, and the like.

Once malicious adware is on a computer it might carry out a variety of unwanted tasks, such as track a user's location, search activity, and web page viewing history, Then the malware developer can sell this information to third parties. Programs that can detect, prevent, and remove adware are available. Often, they are free or come as part of antivirus software. Some popular free options include Kaspersky, Avast, Bitdefender, and AVG.

The Bottom Line

Not all adware is dangerous but you do need to protect your computer and yourself with antivirus software. And don't click on an ad or link before determining its legitimacy.