Facebook is one of biggest social platform currently having 1.9 billion active users which means 7 out 2 guys on Facebook. if one can identify the right audience, they can easily promote their business. At the same time one can enjoy the platform and can develop there brand through it. it is the best thing in the market for marketing.
Facebook provides almost everything for a marketer starting from audience, community, platform. one need to be smart enough to take the advantage;)