With the rise of social networking & bookmarking, sharing the content on the web helps increase traffic & also improves branding. There are several social bookmarking sites & also websites where content can be shared. Some of the top such sites are Digg, reddit, google+, Stumbelupon, Delcious, Facebook, Twitter, scribd & others. Some of these sites are popular for tech, gossip, politics & others.
1) Social Sharing Buttons helps increase traffic to the website. By submitting the sites to Digg, Reddit & others, users will vote on it & if they like, they will visit the site to access the content. Thus increasing the traffic.
2) It helps in branding of the site. As more & more people share the content, people will start searching for it in search engines & thus helping in branding.
3) It helps in creating of communities. If people start liking content from websites, it helps in creating a community of like minded people who will be great asset for the sites.
4) Other websites start linking to the articles, blogs & others which will help increasing trust rank & hence better Google rankings.