The social network Bluesky has been growing at a rapid rate ever since the US presidential election concluded. The site has added over 11 million users since the election on Nov. 5, pushing it to over 25 million users by Dec. 17.  Star Wars star Mark Hamill recently joined the site, proclaiming himself a "Twitter quitter." And Rep. Alexandria Ocasio-Cortez of New York became the first person to reach over 1 million followers on the platform. That's the first for any Bluesky account except the company's own. Ocasio-Cortez has 1.1 million followers as of Tuesday.

There are at least two ever-changing counters created by Bluesky users that track the site's numbers. One counter is from Theo Sanderson, a professor at the London School of Hygiene & Tropical Medicine; another counter is by a user who simply goes by Natalie on the site.

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A representative for the company said in an email last month that the site had added over 1 million users a day in the period immediately after the election. That rate equals about 12 new users per second. The 25 million user mark compares to 9 million users in September.

Bluesky may be surging, but the site has a way to go to catch competing sites. Forbes reports that X has 588 million global users as of September, a drop from 611 million in April. Threads, Meta's competitor to X, has more than 275 million daily users.

The X factor

Although there's no way to determine how many new users left because of X owner Elon Musk's public support for President-elect Donald Trump, many Bluesky users are referencing the election in their first posts. Wired reports that many Taylor Swift fans, a group that once had a large presence on X, are switching to Bluesky.

Bluesky is a social media platform that shares many similarities with X, formerly known as Twitter. X underwent a number of changes after billionaire Musk bought the site and retired legacy blue check marks showing verified accounts, reinstated previously banned accounts and started a new subscription program. 

On Oct. 16, X announced that it was changing its block function, which allowed people to stop others from seeing their messages on the site. Accounts that have been blocked can now see that person's posts on X if the posts are set to public, though they cannot reply, like or repost them. "That's not blocking," one X user replied. "That's supporting stalking."

The following day, Oct. 17, Bluesky shared a post announcing that it had welcomed 500,000 people in just one day. "First day here," one Bluesky user wrote in response to the company's post about its growth. "Just getting my feet wet. Was a longtime Twitter user but it's a shell of what it used to be."

X has also updated its terms of service so that any lawsuits by users against the service must be handled by a federal court in north Texas "whose judges frequently deliver victories to conservative litigants in political cases," The Globe and Mail reports.

These latest changes may have sparked the rise of interest in Bluesky, which saw a surge in user accounts earlier this year when X was blocked by courts in Brazil (the block was later lifted when X paid a fine). According to The New York Times, users say Bluesky is the app that comes closest to mimicking X.

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Here's a look at what you need to know about Bluesky.

How do I sign up?

To join, just go to the main page to create an account. You can download the Bluesky app for iOS or Android, or use Bluesky on your desktop. 

It'll ask for your email address and phone number (to send an authentication code) and tell you to choose a username and password. Then you're in.

How is Bluesky similar to X and Threads?

If you're accustomed to X, Bluesky's design and purpose should make sense to you.

The site uses vertically scrolling messages with small round photo avatars for users and icons under messages showing how many comments, likes and reposts they've received. It looks pretty similar to X's format and Meta's Threads, which is the current No. 2 free app on the App Store, behind Bluesky.

Read more: Time to Cut Off Your X (Twitter)? Here's How

Who's behind it?

Here's another Twitter/X connection: Twitter co-founder Jack Dorsey was formerly on the board of directors, and the Bluesky project began in 2019 when he was Twitter CEO. Jay Graber is the Bluesky CEO. 

Even Bluesky's name is related to X's former name. Dorsey confirmed a Bluesky user's speculation that the name ties in to Twitter's bird mascot, the idea being the bird could fly even more freely in an open blue sky. Dorsey left the board in May, apparently because the service added moderation tools.

Even though the name of the site doesn't capitalize the S in "sky," it's pronounced "blue sky." Don't rhyme it with "brewski."

The app is built on something called the authenticated transport protocol, or AT, a social media framework created by the company and made up of a network of many different sites.

And how is Bluesky different?

Domains as handles

For one thing, you can set your domain as your handle, if you wish. This could help with verification, which became a heated issue for Twitter once Musk began removing blue check marks from verified accounts that refused to pay a monthly fee.

"For example, a newsroom like NPR could set their handle to be @npr.org," the Bluesky Social company blog notes. "Then, any journalists that NPR wants to verify could use subdomains to set their handles to be @name.npr.org. Brand accounts could set their handle to be their domain as well."

Moderation

Moderation is also different. Another blog post says that Bluesky is already using automated moderating, and has a system of community labeling, which is described as "something similar to shared mute/block lists."

Users of many social media platforms are shown posts from a feed selected for them by an algorithm, though you can influence that by following or blocking certain accounts. But Bluesky wants to give you a chance to pick from a variety of different algorithms to determine what you see. 

You can mute accounts, which prevents you from seeing any notifications or top-level posts from them, or you can block accounts, which takes that a step further, meaning you and the other account both cannot see or interact with each other's posts. And you can report posts or accounts for abuse. The blocking option may be of special interest to users who were unhappy with X's recent change in its blocking behavior.

A couple of features -- being able to hide replies to your posts and detach your posts from other users' posts that quote yours -- are designed to stop pile-ons and other toxic behavior.

Keeping connections

It's possible that creators who acquire a following on Bluesky might one day be able to keep connections with those who follow them, even if the service itself changes.

If you want to follow the people you followed on X, the third-party Sky Follower Bridge is a free tool that scans your follower list and follows accounts with the same names on Bluesky. You'll get a few false positives and a lot of dormant Bluesky accounts, but overall we've found it works very well.

Custom feeds

Algorithms are the rules that determine how content is filtered and recommended to users. Bluesky has something it calls custom feeds, which allows you to choose the algorithm that determines what you see.

"Imagine you want your timeline to only be posts from your mutuals, or only posts that have cat photos, or only posts related to sports -- you can simply pick your feed of choice from an open marketplace," a blog post on the site says. A longer post goes into more detail about custom feeds and algorithmic choice. Click the hashtag icon on the bottom of the app to add and discover new feeds.

Developers can use the site's feed generator starter kit to create a custom feed, and the site promises that eventually, the tools will be easy enough that the rest of us can build custom feeds.

Starter packs

Want to jump right in to Bluesky by following a curated list of people? You can follow starter packs, which are lists created by users and usually themed. CNET has a lengthy explanation here, but in short, they're similar to what X calls lists, and are a good way to get a solid feed going that caters to your interests.

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Who's using it?

Here's a small list of some of the people and groups you'll see posting on Bluesky.