Twitter introduced its first verified-account badges in 2009.
The badge was created to help users identify authentic accounts belonging to public figures, celebrities, organizations, and other notable entities. It became especially useful because impersonation was already a problem on a rapidly growing social network.
Twitter initially handled verification through an application process and used the badge as a signal of identity authenticity. Verification was not originally a paid product; that model changed substantially after the acquisition of Twitter.
A common mix-up is confusing the launch of verification with the later blue-check subscription system. The original badge was an identity-confirmation feature, while the later system connected verification with paid subscriptions and other account benefits.