What Is Bluesky and Why Are People Clamoring to Join It?

The buzz this week around Bluesky, a new social media platform being called Twitter 2.0, has been intense. Prominent Twitter users such as Representative Alexandria Ocasio-Cortez, Democrat of New York, and the model and cookbook author Chrissy Teigen have joined. Thousands of others are begging for invitations to it.

Some Twitter users have been looking for an alternative social platform since Elon Musk bought the company last year and then changed the service. Bluesky’s users say the app — which was funded by a Twitter founder, Jack Dorsey — has come the closest to mimicking Twitter’s tone and feel.

Here’s what to know about it.

What is Bluesky?

Bluesky is a social network that offers many of the same core features that Twitter does. Users can post short text and photo updates, reply to each other and share other people’s posts.

The app, which is still in development, became available for iOS devices in February and for Android devices this month.

How is Bluesky different from Twitter?

Jay Graber, Bluesky’s chief executive, said in a blog post last month that it was no coincidence that the app looked like Twitter. But unlike Twitter, Bluesky plans to be a decentralized system, meaning people may eventually be able to build their own apps and communities within it. Ms. Graber said it was designed that way so that no individual could create rules for the entire Bluesky community.

Bluesky also operates using an “open protocol.” This is unusual because social media platforms have traditionally been walled gardens, meaning that what is posted on individual platforms remains only on that platform. For instance, your tweets show up on Twitter and your photos show up on Instagram, but they cannot be easily cross posted across those social networks.

But because Bluesky is trying to be more open, it could someday allow posts to flow between different social media platforms with ease.

Last month, a Bluesky user speculated that the app’s name came from Mr. Dorsey’s desire to transform Twitter into an open protocol, freeing Twitter’s bird mascot to a blue sky. Mr. Dorsey responded, “Yes.”

How do you join Bluesky?

With Bluesky still under development, it is currently invitation only. The app is building moderation tools before opening up to the general public, Ms. Graber said in a post on the platform last month. To sign up, people need an invitation code from a current user.

Why has Bluesky become popular?

Since Mr. Musk bought Twitter, he has changed the service by removing restrictions around online speech on the platform and changing its verification practices. Those have led to some user confusion, as well as to an increase in misinformation and hate speech on the platform.

As a result, Twitter users have tested out alternatives. In recent months, some have migrated to Mastodon, another decentralized social media platform that has said it aims to be “a viable alternative to Twitter.”

Bluesky was originally limited to a small group of tech insiders. On Thursday, several prominent Twitter accounts and public figures — such as Ms. Ocasio Cortez, Ms. Teigen and social media star Dril — joined the platform, creating buzz around it.

Bluesky’s users appear to be having fun with the app’s similarities to Twitter, including calling posts on the app “skeets,” as a play on tweets. Not even a plea from Ms. Graber on Thursday to change that name seems to have deterred them.

Kate Conger contributed reporting.