"Today, we're launching Fleets so everyone can easily join the conversation in a new way -- with their fleeting thoughts," Twitter's Design Director Joshua Harris and Product Manager Sam Haveson wrote in a blog post.
Meant for sharing momentary thoughts, Fleets only stick around for 24 hours.
Twitter said that its tests of Fleets in Brazil, Italy, India, and South Korea, were encouraging.
The results showed that Fleets helped people feel more comfortable joining the conversation and Twitter saw that people with Fleets talk more on Twitter.
"Those new to Twitter found Fleets to be an easier way to share what's on their mind. Because they disappear from view after a day, Fleets helped people feel more comfortable sharing personal and casual thoughts, opinions, and feelings," Harris and Haveson wrote.
"These are early findings from our tests and we're excited to learn more about how Fleets are used by you."
One can Fleet text, reactions to tweets, photos or videos and customise their Fleets with various background and text options.
To share a tweet in a Fleet, you need to tap the "Share" icon at the bottom of the Tweet and then tap, "Share in Fleet."
Then, add what you think about it with some text or emojis.
Twitter said that stickers and live broadcasting will be available in Fleets soon.
"Your followers can see your Fleets at the top of their home timeline. Anyone who can see your full profile can see your Fleets there too. If you have open Direct Messages, anyone can reply to your Fleets," Harris and Haveson wrote.