Google has launched a Personal Blocklist extension for Chrome on the Chrome Web Store, available in English, French, German, Italian, Portuguese, Russian, Spanish, and Turkish. The search giant's goal is to fight content farms, which are sites with shallow or low-quality content. With the launch of the extension, the company is getting another piece of data (explicit feedback from users) that it can use in its algorithms. Here is the official extension's description:

The personal blocklist extension will transmit to Google the patterns that you choose to block. When you choose to block or unblock a pattern, the extension will also transmit to Google the URL of the web page on which the blocked or unblocked search results are displayed. You agree that Google may freely use this information to improve our products and services.

Once installed, when you block a site with the extension, you won't see results from that domain again in your Google search results. At the same time, the extension will send blocked site information to Google, which in turn will study the resulting feedback and explore using it as a potential ranking signal for its search results. Naturally, you can always revoke a blocked site by clicking the undo link at the bottom of the search results. You can also edit your list of blocked sites by clicking on the extension's icon in the top right of the Chrome window.