There are three types of companies described in the document: mainstream, independent, and niche. Mainstream companies have large user bases like Instagram which had over 300 million users by 2014. Independent companies operate in a specific location or industry like Abbey Records which was founded in Queens, NY and had its first hit record in 1950. Niche companies focus on specialized products or services, for example Quidsi operates diapers.com and expanded into cosmetics, demonstrating how niche online retailers can still attract many customers.