Influence of celebrity endorsement/endorsers on consumer behaviour: A study of source credibility theory and consumer decisions through Instagram (the case of beauty products)

The purpose of this research is to explore Instagram user perceptions of celebrity versus micro-celebrity beauty product endorsements, and their influence on consumers' purchasing behaviours. The Source Credibility model was used in this study to identify themes when analysing user comments.The study included five celebrity and five micro-celebrity influencers as case studies. This study has implications for the theory and practice of social media marketing, influencer marketing, brand endorsement, and the understanding of Instagram user behaviour. Influencer -consumer engagement in the endorsement of brands is still very much limited. Authentic Engagement emerged from the research as the central theme and an important aspect of influencer marketing. Therefore, this study contributes to the body of knowledge by analysing user comments on beauty product endorsements in multiple case studies of USA celebrities and micro-celebrities. The contribution to the community lies in the fact that celebrities and micro-celebrities are in practice presented by high-profile social media marketing agencies in the influencer industry in which talent agents and managers, brands, marketing agents, and marketing event organisers are stakeholders.This research has demonstrated that micro-celebrity endorsements can potentially influence users' propensity to purchase beauty products as opposed to the influence of celebrities based on the Instagram analysis of the posts by followers of the selected influencers.