Perhaps the best feature about LinkedIn is the fact that you can post any recommendations from your previous customers or colleagues about your business right to your LinkedIn business site (and we all know just how important testimonials and third party endorsements are!) LinkedIn gives you the chance to really build up your brand in a community that is quite similar to you. As LinkedIn is more about businesses connecting with other businesses, you’ll be among more like-minded people – and you may be able to pick their brains for more marketing ideas.
Mobile social media tools can be used for marketing research, communication, sales promotions/discounts, informal employee learning/organizational development, relationship development/loyalty programs, and e-Commerce. Other applications include marketing research, communication, sales promotions and discounts, relationship development and loyalty programs, and informal employee learning/organizational development is facilitated by the social media.
Social media becomes effective through a process called "building social authority". One of the foundation concepts in social media has become that you cannot completely control your message through social media but rather you can simply begin to participate in the "conversation" expecting that you can achieve a significant influence in that conversation.
There are a number of ways to make money on social media: You can promote your own products or services, you can become an affiliate of other companies or you can set up a YouTube channel that comes with paid advertising. All of these strategies have the potential to become lucrative, but only if you are able to build a substantial following. You won't be able to raise any significant funds from your personal Twitter or YouTube account if you only have 10 followers. So how do you build a large social media following? According to Yahoo, to ensure social media money-making success, do the following:
Efforts to combat selective exposure in social media may also cause an increase in political polarization.  A study examining Twitter activity conducted by Bail et. al paid Democrat and Republican participants to follow Twitter handles whose content was different from their political beliefs (Republicans received liberal content and Democrats received conservative content) over a six week period.  At the end of the study, both Democrat and Republican participants were found to have increased political polarization in favor of their own parties, though only Republican participants had an increase that was statistically significant. 
Cyberbullying/Cyberstalking: Children and teenagers are especially susceptible to cyberbullying because they take more risks when it comes to posting on social media. And now that we all interact on social media via our mobile devices, most major platforms make it possible to share our locations, opening up the doors for cyberstalkers to target us.