The 33,000-plus-store multinational chain is a shining example of taking a grassroots community and transforming it into a global phenomenon. Every single person involved with Starbucks is united under its iconic siren logo. From farmers and suppliers to employees (referred to as “partners”) and patrons, the company consistently creates a single thread of community that makes everyone feel like they're part of something larger than themselves.

Starbucks is also well-known for a culture of social change and positive impact, from its stores to its online presence.

British fitness apparel brand Gymshark knows that sometimes the best approach to community is laughter. Its main Twitter account is less focused on marketing activewear and more on bringing fans together with funny and relatable tweets. It now boasts a Twitter community of nearly 330,000 members,...