Ad filtering or ad blocking is a service which removes or alters advertising content in a webpage. This content can be represented in a variety of ways including pictures, animations, text, or pop-up windows. More advanced filters allow fine-grained control of advertisements through features like blacklists, whitelists, and regular expression filters. Certain security features also have the effect of disabling some ads.
The immediate benefits include cleaner looking webpages free from advertisements and lower resource-usage (bandwidth, CPU, memory, etc.). One drawback is that advertisements are a major source of revenue for many websites. However, the actual loss of revenue, when present, is difficult to measure.
Some web browsers support ad filtering through built-in features and plugins. A number of popular browsers include a pop-up blocker, such as Microsoft’s Internet Explorer, Mozilla Firefox , Opera Software’s Opera, and Apple Computer’s Safari. All of these browsers support extensions and/or plugins which can include ad filters. For example, Adblock is a popular extension for Firefox.
A number of external applications offer ad filtering as a primary or additional feature. A traditional solution is to customize an HTTP proxy (or web proxy) to filter content. Proxies may reside on and serve a single computer or serve a number of clients over a network. These programs work by caching and filtering content before it is displayed in a user’s browser. This provides an opportunity to remove not only ads, but content which may be offensive or inappropriate. Popular proxy software which can be used as effective ad filters include: Privoxy, Squid, Proximodo, and Proxomitron.
Common advertising techniques
- Pop-up ads
- Plain text
- Ad banners
- Flash animations
- Keyword hyperlinks (for example Vibrant Media’s IntelliTXT)
- Browser plugins/extensions (often labeled as adware)
- External applications