What Are Social Media? 
And what do these buttons do?

Social Media

Social media let you use the Web to interact with others. This could be through social networking sites like Facebook or Twitter, where you can communicate with family, friends and acquaintances. Or it could be through social bookmarking services, like StumbleUpon, and Delicious, where you bookmark Web pages you like and share them with other users of the same service.

How to use these buttons

These Facebook and Twitter buttons let you easily share the Web page you just read by adding it to your favorite social media tool. How? Simply click on its button on the page. There's nothing to download or install.

If you're not yet using Facebook or Twitter, you can register for it after clicking on its button. Once your account is up and running, you'll be able to share the Web page with friends and family.

Of course, you're not limited to Facebook and Twitter. You can add a Web page to any other service you already use.