The app went live on Apple and Android app stores in 100 countries at 2300 GMT on Wednesday, and will run with no ads for now.
Threads was introduced as a clear spin-off of Instagram, which offers a built-in audience of more than two billion users, thereby sparing the new platform the challenge of starting from scratch.
1. Threads looks nearly identical to Twitter in many ways. Users can post mostly text-based messages to a scrolling feed, where people who follow them and whom they follow can reply. People can also post photos or video to the app.
3. Threads will operate seamlessly with other platforms, which could appeal to creators and influencers so they do not have to start from scratch on each app.