Adblock: Good or Evil?

Tweet

Many Firefox user like to use Adblock, because it allow them to block those annoying ads & increased the overall display speed by not loading certain elements (Ads) on the website. However, some webmaster hate Adblock so much that they go as far as blocking all the Firefox users! Because they claimed that Adblock is illegal, & it's killing many Ad support website that providing FREE contents to the public. So, what do you think? Is Adblock Good, or Evil?