Facebook then launched a rival app called Slingshot."
New York, Aug 13 - The messaging app Snapchat has left Twitter behind to become the third most used social media app among the millennial group - 18 to 34 year olds.
Almost a third of the 18 to 24-year-olds now use Snapchat, compared to 23.8 percent of Twitter app users, said the latest Mobile Metrix report by US internet analytics company comScore.
Facebook is still the most popular social media app with 75.6 percent people using it, followed by Instagram with 43.1 percent users.
At 32.9 percent, Snapchat's popularity has more than doubled from 12 percent in November last year.
Vine is used by 10.7 percent of millennials while Pinterest has 17.9 percent users.
At the bottom is Tumblr with 6.3 percent users.
Snapchat's popularity is also growing among 25 to 34-year-olds and in the over-35 age group - albeit more slowly than among the younger age group, the report said.
Last year, its co-founder Evan Spiegel turned down a $3 billion acquisition bid from Facebook.
Facebook then launched a rival app called Slingshot.
Instagram, which is owned by Facebook, followed this with the launch of Bolt.