PPC is essentially a model of digital marketing in which advertisers have to pay a certain amount of fee every time someone clicks on their ad. In other words, it is a way to buy web traffic instead of earning it organically. These ads are usually displayed on search engines linking search engine marketing and PPC inextricably.
Online marketing efforts that are initiated through various social media platforms like Twitter, Facebook, and Instagram (being some of the more popular ones) is called social media marketing.
The combination of social media management which is the process of building large organic communities on social sites with social media advertising helps funnel new followers into these online communities. Engagement with members of these communities is then leveraged to promote products, services, or ideas.
Campaigns like these can be very effective when assisted with a knowledgeable and experienced social media strategist. An expert in social media, working for a particular brand is capable of managing social media, communicating directly with the followers, and noting social media analytics.