Social media marketing is the process of gaining website traffic or attention through social media sites.
Social media marketing programs usually center on efforts to create content that attracts attention and encourages readers to share it across their social networks. The resulting electronic word of mouth (eWoM) refers to any statement consumers share via the Internet (e.g., web sites, social networks, instant messages, news feeds) about an event, product, service, brand or company. When the underlying message spreads from user to user and presumably resonates because it appears to come from a trusted, third-party source, as opposed to the brand or company itself, this form of marketing results in earned media rather than paid media
Twitter allows companies to promote their products in short messages limited to 140 characters which appear on followers’ home pages
Facebook pages are far more detailed than Twitter accounts. They allow a product to provide videos, photos, and longer descriptions, and testimonials as other followers can comment on the product pages for others to see. Facebook can link back to the product’s Twitter page as well as send out event reminders.
Google+, in addition to providing pages and some features of Facebook, is also able to integrate with the Google search engine. Other Google products are also integrated, such as Google Adwords and Google Maps. With the development of Google Personalized Search and other location-based search services, Google+ allows for targeted advertising methods, navigation services, and other forms of location-based marketing and promotion. Google+ can also be beneficial for other digital marketing campaigns, as well as social media marketing.
LinkedIn, a professional business-related networking site, allows companies to create professional profiles for themselves as well as their business to network and meet others.
Instagram has proven itself a powerful platform for marketers to reach their customers and prospects through sharing pictures and brief messages.
YouTube is another popular avenue; advertisements are done in a way to suit the target audience. The type of language used in the commercials and the ideas used to promote the product reflect the audience's style and taste.
Also, the ads on this platform are usually in sync with the content of the video requested, this is another advantage YouTube brings for advertisers.
Also many other platform like digg, MySpace, Blogger, WordPress, tumblr,Friendster,Hi5,Xing, Bing, Flickr,Vimeo,Yahoo,Delicious, Pintrest, Scribd,SlideShare etc.