Source: http://en.wikipedia.org/wiki/Social_media_marketing
Marketing has grown and adapted to the technology used nowadays in order to get their message across to their audience. Social media is one of the most used ways on how marketing can be displayed online which is a way to gain attention for their good or service. On some social media site such as Facebook and Twitter; advertisements will come up in their feeds due to companies paying to do a single post to advertise their product.
It's one of the easiest and cheapest ways for companies to get advertise through the internet without having to do much. They rely on the audience that use social media in order to communicate with their friends to share their thoughts or wants for their good or service.
An example would be a launch of a new TV series that's about to premiere such as "Chasing The Saturdays" by E! Entertainment. As the date got closer towards the first broadcast of the new series; they set up a account on two of the most popular social media sites of today which are Facebook and Twitter. They created a facebook page for the new show so they were able to keep track of the amount of people who were watching from Facebook and also a twitter page to keep track of the number of followers the show currently has. The point of creating the pages on social media networks was to keep the viewers of the show updated with when the next episode will be out and some exclusive news or behind-the-scene work for the show which was also a way to entice the audience to keep watching the show.
However, social media nowadays is majorly used by the younger generation. This can result to a problem that particular advertisements that show up on their feed will not appeal to their wants or tastes. An example would be an advert for cheap flights showing up on their feed. The company advertising the flights would've paid the social media site to send out the advert to everyones feed in a particular region but sometimes it can be age or gender. An 13 year old teenage girl receiving this type of advertisement would not see this as very attractive or appealing to their wants as an individual but then again it depends whether she may have a craving to go on holiday and thus may go on to persuade her parents and family to go on holiday while the flights are still cheap.