Since social media marketing first came to be, strategists and markets have been getting smarter and more careful with the way they go about collecting information and distributing advertisements. With the presence of data collecting companies, there is no longer a need to target specific audiences. This can be seen as a large ethical gray area. For many users, this is a breach of privacy, but there are no laws that prevent these companies from using the information provided on their websites. Companies like Equifax, Inc., TransUnion Corp, and LexisNexis Group thrive on collecting and sharing personal information of social media users. In 2012, Facebook purchased information from 70 million households from a third party company called Datalogix. Facebook later revealed that they purchased the information in order to create a more efficient advertising service.
Social networking websites allow individuals, businesses and other organizations to interact with one another and build relationships and communities online. When companies join these social channels, consumers can interact with them directly. That interaction can be more personal to users than traditional methods of outbound marketing and advertising. Social networking sites act as word of mouth or more precisely, e-word of mouth. The Internet's ability to reach billions across the globe has given online word of mouth a powerful voice and far reach. The ability to rapidly change buying patterns and product or service acquisition and activity to a growing number of consumers is defined as an influence network. Social networking sites and blogs allow followers to "retweet" or "repost" comments made by others about a product being promoted, which occurs quite frequently on some social media sites. By repeating the message, the user's connections are able to see the message, therefore reaching more people. Because the information about the product is being put out there and is getting repeated, more traffic is brought to the product/company.
When would this be useful? If your site has a blog with public commenting turned on, links within those comments could pass your reputation to pages that you may not be comfortable vouching for. Blog comment areas on pages are highly susceptible to comment spam. Nofollowing these user-added links ensures that you're not giving your page's hard-earned reputation to a spammy site.
Social media itself is a catch-all term for sites that may provide radically different social actions. For instance, Twitter is a social site designed to let people share short messages or “updates” with others. Facebook, in contrast is a full-blown social networking site that allows for sharing updates, photos, joining events and a variety of other activities. https://libertymarketing.tumblr.com/