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Influencer Marketing: A Research Guide

As a marketing strategy, companies hire individuals with a large social media following to promote products through their personal accounts. Use this guide to research the business of influencer marketing, current issues and regulations in the industry.


Harris & Ewing, photographer. National Style Show Models. 1914. Library of Congress Prints and Photographs Division.

Influencer marketing is the action of paying people to personally promote a product, usually through social media platforms such as Instagram and YouTube. A survey by the Association of National Advertisers External found that 75% of marketers use influencer marketing in their promotion strategy.1 As the influencer marketing industry grows, some universities are offering courses in influencer strategies and influencer-related public relations.2 Influencers are those who can reach and resonate with a large audience, but the size of that audience can vary:

  • Mega-influencers are celebrities famous from acting or other highly public work with more than a million followers;
  • Macro-influencers are typically "internet famous," and are generally what people refer to when talking about "influencers" and have between 100,000 and a million followers;
  • Micro-influencers are more niche, known in their industry, and can have follower counts between 1,000 and 100,000; and
  • Nano-influencers, who have a more immediate relationship with their followers, either because of their content or geographic focus, and usually have less than 1,000 followers.3, 4

This guide provides an overview for individuals interested in researching social media influencers, businesses that use influencer marketing, and current issues in influencer marketing.


Useful keywords for searching this topic include: Influence marketing, influencer marketing, social media influencer, brand marketing, endorsements, digital marketing, social media marketing, content creators

When searching in the Library of Congress Online Catalog, try combining both keywords and subject headings to narrow your search results.

About Business Reference Services

Part of the Science, Technology & Business Division at the Library of Congress, Business Reference Services is the starting point for conducting research at the Library of Congress in the subject areas of business and economics. Here, reference specialists in specific subject areas of business assist patrons in formulating search strategies and gaining access to the information and materials contained in the Library's rich collections of business and economics materials.


  1. “Advertisers Love Influencer Marketing,” Association of National Advertisers, April 3, 2018, External. Back to text
  2. Kalhan Rosenblatt, “Big 'gram on campus: At USC, students train to become influencers,” NBCNews, March 13, 2020, Back to text
  3. Spana Maheshwari, “Are You Ready for the Nanoinfluencers?,” The New York Times, November 11, 2018, External. Back to text
  4. Kaya Ismail, “Social Media Influencers: Mega, Macro, Micro or Nano,” CMSWire, December 10, 2018, External. Back to text