Twitter reached 100 million monthly active users in 2011. The milestone was reported in September 2011, marking a major step in the service’s rapid expansion from a niche microblogging platform into a global social network.
Twitter’s growth was closely tied to its real-time nature, mobile accessibility, and use during major news and cultural events. Users could follow conversations without needing reciprocal friendships, helping the platform spread quickly among journalists, celebrities, activists, and ordinary users.
A common mix-up is confusing monthly active users with daily activity or total registered accounts. In 2013, Twitter had more than 100 million daily active users, while its monthly active-user figure was already substantially higher. The company later reported more than 200 million monthly active users in December 2012 and 255 million by March 2014.
The 2011 milestone therefore sits between Twitter’s early breakout years and its later period of large-scale international growth.