Social media influencers are credible individuals with significant followings on networks like Instagram and TikTok, impacting their audience's purchasing choices through authentic content. They are categorized into mega, macro, and micro influencers based on their follower counts and levels of engagement, with micro influencers often fostering closer relationships with their audiences. The influencer marketing landscape is evolving, emphasizing authenticity and transparency, with future trends leaning towards advanced technology integration for more personalized marketing strategies.