A few considerations
Keep in mind that a blocker may not always be able to distinguish invasive Web elements from benign ones. For example, some can prevent social-media buttons from appearing, thus thwarting your attempts to "like" or tweet about something.
There's one other consideration, and that's the funding behind the blocker. While most of the apps that I looked at are free or open-source, supported exclusively by donations, at least one, DoNotTrackMe, employs a freemium model (charging a subscription fee if you want advanced features), while Ghostery asks you to provide usage data. Of the six tools reviewed here, only Adblock Plus has an "acceptable ads" feature that allows advertising from Google and other paying companies, and it's turned on by default. But you can easily disable it if you want a totally ad-free experience.
Speaking of which, it's one thing to protect your privacy, but should you really turn off the ads that pay for so much good online stuff? It's food for thought, and if you want a big-picture discussion of ad-blockers and how they may or may not impact the Web as a whole, you may want to read Robert Mitchell's Ad blockers: A solution or a problem?.
Price: Free; accepts user contributions
Compatible with: Chrome, Firefox, Opera, Safari
Not to be confused with Adblock Plus (which originated as a Firefox extension), AdBlock currently works with Chrome, Safari, Firefox and Opera browsers.
What it does: Blocks ads, of course. With AdBlock running, you shouldn't encounter any banners, pop-ups or video ads. However, the plug-in makes no claim to prevent tracking.
How it performed: Because AdBlock isn't compatible with Internet Explorer, I confined my testing to Chrome. The tool offers some useful toggles from its toolbar pull-down menu, including options to pause the plug-in, disable it for just the current page or disable it for the entire domain. This last could come in handy if you discovered a compatibility issue with, say, a site's comment system. I never encountered any such issues.
Rather, AdBlock worked exactly as advertised, keeping ads at bay virtually everywhere I went. It made for a blissfully ad-free viewing experience at Crackle and YouTube. Hulu actually detected the presence of AdBlock and flashed a message asking me to enable ads for the site. After about 30 seconds, however, the message disappeared and the show began playing. So while I didn't have to actually watch the commercial, I didn't enjoy uninterrupted viewing.
Also, AdBlock tallied just five blocked items at TMZ.com, while Adblock Plus counted 14. Why the difference? It's tough to say, because neither program indicates exactly what's been filtered. The only visible difference was that, while AdBlock reformatted the page content to compensate for eliminated ads, Adblock Plus left a few empty spaces.
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