Share Buttons by AddToAny is a popular social media sharing kit with more than 2 million digital downloads. It is a free plugin which you can download from WordPress plugin repository, make a few easy configuration settings and easly display sharing icons for popular social networking websites like Facebook, Twitter, Google+, Pinterest, StumbleUpon and there are many many more.
Installation & Usage: Install and activate Share Buttons by AddToAny. After activation it automatically displays a sharing block of buttons under your blog posts.
The plugin is highly customizable and provides you a group of very useful options which you can access from your admin area Dashboard -> Settings -> Add To Any admin page.