The Brief: A blue check mark in a circle on someone's social media page indicates that their identity has been officially verified by the platform.
DEEP DIVE
Blue checks, also known as verification badges are often indicators that someone is a celebrity or influencer. They are a sought-after item for those seeking internet fame.
Instagram, Twitter, YouTube, Pinterest, SoundCloud, and Facebook use similar verification processes and indicators. Verification badges usually come with increased security settings to protect the integrity of popular public accounts. The blue check system helps stop fake celebrity accounts from gaining large followings. It also allows those who have been verified to show off their clout. 
How To Get A Blue Check:
Blue check marks are typically reserved for people and brands who are famous and who are at-risk for impersonation, On Instagram, only accounts for well-known figures and brands are eligible for verification. Sometimes Twitter allows account users to apply for verification. YouTube grants verification badges to channels with 100,000 followers or more. Facebook verifies certain personal profiles and most business pages.