This chart shows data on the 20 most popular social networks worldwide as of October 2018, ranked by number of active accounts.
Market leader Facebook was the first social network to surpass 1 billion registered accounts and currently sits at 2.23 billion monthly active users. Sixth-ranked photo-sharing app Instagram had 1 billion monthly active accounts.

Statistic: Most famous social network sites worldwide as of October 2018, ranked by number of active users (in millions) | Statista
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