What you need to know about Threads, Instagram's new Twitter ...

While most features mimic those of Twitter, its user interface design resembles Instagram’s, with the same heart, comment and share buttons and similarly placed tabs.

Threads joins a growing list of platforms such as Bluesky and Spill, as well as older competitors like Mastodon, looking to challenge Twitter’s dominance in the microblogging sphere.

Once logged in, new users who have Instagram accounts are told their account must retain the same usernames, but are able to a different bio and link to their profiles. Verified Instagram users will take their check marks to Threads, as well. Users can then choose to follow in bulk all accounts they already follow on Instagram, which includes pre-following anyone who has not yet joined Threads.

In his first thread, Zuckerberg wrote "Let’s do this. Welcome to Threads" with a fire emoji. It's dated from two days ago, when some big names appeared to have early access.

Others on the app as of Wednesday's launch included Jennifer Lopez and Tom Brady, as well as brands like HBO and publishers like Teen Vogue.

Accounts that users have already blocked on Instagram will also be automatically blocked on Threads. Those who wish to limit interactions can choose whether to allow replies from everyone, accounts they follow or mentions — users whom they directly tagged in a thread — only. They can also choose to restrict mentions of themselves to just accounts they follow or to disallow them entirely.

Instagram’s community guidelines will be enforced on Threads, and users can report one another for violations. As on Twitter, users can choose to hide specific words or phrases from their feeds.

Before launch, Meta had reportedly granted selected creators early access to test its features and encourage people to join.