An online social network focused on a particular brand can help build that brand by:

• Offering a place to for those who are loyal to the brand to connect with one another, and to share feelings and experiences around that brand
• Giving the organization insight into how users view the brand and what they value in the brand
• Providing a conduit for the organization to support and reward those loyal users.
• Providing a marketing channel for helping to guide brand development and market and test new approaches
  

An online social network is, by definition, a group of individuals with a common interest.  When that interest is focused on a particular product or brand, being able to communicate ones feelings and experiences with others who are also emotionally engaged can strengthen participants' loyalty to that brand.

Since the most engaged and interested users are likely to participate in that online community, the organization has an excellent pipeline into user perceptions, and a means of identifying those loyal users that can permit the organization to support and reward them as well as to market to them.