AdBlock Plus is a Chrome or Firefox extension that does just what its name suggests.
Odds are you have become skilled at ignoring Internet ads. But every year, advertisers get more
invasive creative at inserting ads in places where they are harder to ignore. As soon as next month, for example, ads will appear in your Facebook newsfeed. It's too soon to say whether AdBlock Plus will remove these forthcoming newsfeed ads, but the extension does an admirable job of removing the current advertising from Facebook and other sites.
Simply install the extension (here for Chrome or here for Firefox) and it automatically starts running (Firefox requires a restart first). In Chrome, you'll know it's running because a small ABP stop-sign icon gets added to the right side of your URL bar. If you consider that an ad, you can remove it in AdBlock Plus's settings. Go to Window > Extensions. Click on the new tab that opens, click the Options link for AdBlock Plus, and choose the General tab, where you'll see a check box for Show icon in address bar.
In Firefox, this icon gets added to the bottom-left corner of your browser window. And to get to AdBlock Plus settings in Firefox, the path is Tools > Add-ons > Extensions.
This little icon is useful, however, if you'd like to create exceptions. If there is a site where you don't mind the ads or would actually like to see them, you can easily disable AdBlock Plus for that site. (In Facebook, for example, AdBlock Plus removes the Ticker along with the ads from the right panel.) To do so, in Chrome you click the stop-sign icon and uncheck the box for Enabled for this site. The icon will be grayed out and ads will return for that site. In Firefox, you click on the icon in the bottom-left corner and choose one of the disable options for removing ads from the current page you are viewing, from all pages on the site you are currently visiting, or disable the extension altogether.
I installed it on both Chrome and Firefox, and the correct English language filter (EasyList) was chosen for me. Filters for other languages can be found on the Filter lists tab of the AdBlock Plus' Options page.
With AdBlock Plus running, you'll see a blank spot where an ad would be on some sites, but on others like CNET, the elements on the page shift around so that the absence of advertising isn't as conspicuous. In Firefox there is an option to hide placeholders of blocked elements, but it doesn't seem to do anything.
For most people, the default settings will suffice. Ads go away and, in my experience thus far, performance is unaffected.