There are arguments that "privacy is dead" and that with social media growing more and more, some heavy social media users appear to have become quite unconcerned with privacy. Others argue, however, that people are still very concerned about their privacy, but are being ignored by the companies running these social networks, who can sometimes make a profit off of sharing someone's personal information. There is also a disconnect between social media user's words and their actions. Studies suggest that surveys show that people want to keep their lives private, but their actions on social media suggest otherwise. Another factor is ignorance of how accessible social media posts are. Some social media users who have been criticized for inappropriate comments stated that they did not realize that anyone outside their circle of friends would read their post; in fact, on some social media sites, unless a user selects higher privacy settings, their content is shared with a wide audience.
Social media marketing has increased due to the growing active user rates on social media sites. For example, Facebook currently has 2.2 billion users, Twitter has 330 million active users and Instagram has 800 million users. One of the main uses is to interact with audiences to create awareness of their brand or service, with the main idea of creating a two-way communication system where the audience and/or customers can interact back; providing feedback as just one example. Social media can be used to advertise; placing an advert on Facebook's Newsfeed, for example, can allow a vast number of people to see it or targeting specific audiences from their usage to encourage awareness of the product or brand. Users of social media are then able to like, share and comment on the advert, becoming message senders as they can keep passing the advert's message on to their friends and onwards.
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. 
Thanks Mike for your comment. I don’t trust Facebook either. There’s been many times where I have seen ads come up on FB of subjects that I’ve been talking about offline. Its happened on more than one occasion which is a bit scary if you ask me. Although I do think FB has had its best days and will gradually fall in user numbers as new and innovative platforms come to market over the next 5 years.
For individuals, social media is used to keep in touch with friends and extended family, network for career opportunities, find people from all over the globe who share a common interest, share content and more. Those who engage in these activities are part of a virtual social network. For businesses, social media is an indispensable tool for finding and engaging with customers, sales, advertising and promotion, gauging trends and offering customer service. Governments and politicians utilize social media to engage with constituents and voters.
^ Patton, George C.; Sawyer, Susan M.; Santelli, John S.; Ross, David A.; Afifi, Rima; Allen, Nicholas B.; Arora, Monika; Azzopardi, Peter; Baldwin, Wendy (June 2016). "Our future: a Lancet commission on adolescent health and wellbeing". The Lancet. 387 (10036): 2423–2478. doi:10.1016/s0140-6736(16)00579-1. ISSN 0140-6736. PMC 5832967. PMID 27174304.
The more time people spend on Facebook, the less satisfied they feel about their life. Self-presentational theory explains that people will consciously manage their self-image or identity related information in social contexts. When people are not accepted or are criticized online they feel emotional pain. This may lead to some form of online retaliation such as online bullying. Trudy Hui Hui Chua and Leanne Chang's article, "Follow Me and Like My Beautiful Selfies: Singapore Teenage Girls' Engagement in Self-Presentation and Peer Comparison on Social Media" states that teenage girls manipulate their self-presentation on social media to achieve a sense of beauty that is projected by their peers. These authors also discovered that teenage girls compare themselves to their peers on social media and present themselves in certain ways in effort to earn regard and acceptance, which can actually lead to problems with self-confidence and self-satisfaction.
Usenet, which arrived in 1979, was beat by a precursor of the electronic bulletin board system (BBS) known as Community Memory in 1973. True electronic bulletin board systems arrived with the Computer Bulletin Board System in Chicago, which first came online on 16 February 1978. Before long, most major cities had more than one BBS running on TRS-80, Apple II, Atari, IBM PC, Commodore 64, Sinclair, and similar personal computers. The IBM PC was introduced in 1981, and subsequent models of both Mac computers and PCs were used throughout the 1980s. Multiple modems, followed by specialized telecommunication hardware, allowed many users to be online simultaneously. Compuserve, Prodigy and AOL were three of the largest BBS companies and were the first to migrate to the Internet in the 1990s. Between the mid-1980s and the mid-1990s, BBSes numbered in the tens of thousands in North America alone. Message forums (a specific structure of social media) arose with the BBS phenomenon throughout the 1980s and early 1990s. When the Internet proliferated in the mid-1990s, message forums migrated online, becoming Internet forums, primarily due to cheaper per-person access as well as the ability to handle far more people simultaneously than telco modem banks.