An influencer is someone who has:
• the power to affect the purchasing decisions of others because of his or her authority, knowledge, position, or relationship with his or her audience.
• a following in a distinct niche, with whom he or she actively engages. The size of the following depends on the size of his/her topic of the niche.
It is important to note that these individuals are not merely marketing tools, but rather social relationship assets with which brands can collaborate to achieve their marketing objectives.