Social media can play at least two roles in the marketing of goods and services.
First, the social media can be used directly by a firm that wants to market its products. The firm can have a Twitter feed or a Facebook page. It can use those media to send out ads and special offers and other such things. It can use the media to try to build a closer connection with its customers. They more they feel “close to” the firm (through receiving its tweets and reading its updates) the more likely they are to remain loyal to that firm.
Second, indirect use of the social media can be important in a firm’s marketing strategy. What a firm would really like is for people who have a lot of Twitter followers or Facebook friends to promote their products. If those people say good things about a given product, they might have more of an impact than actual advertisements because their endorsements will seem more real and sincere. Therefore, firms can do things like giving free samples to such “opinion leaders” in hopes that they will promote the products to their friends and followers.