Twitter killer? Here’s what to know about Threads, the new app from Meta.

The Threads app, operated by Meta Platforms, on a smartphone, beside an Instagram logo.Paul Hanna/Bloomberg

Gab. Parler. Mastodon.

A whole lot of companies have built social networks to challenge Twitter, to no avail.

But this time, things just might be different. Threads, the new Twitter lookalike from Instagram, launched on Wednesday night in the United States, the United Kingdom, and Australia. The new network begins life with a massive advantage: About 2 billion existing Instagram users will find it easy to download the Threads app and give it a try.

And that seems to be happening. On Thursday morning, Mark Zuckerberg, chief executive of Meta Platforms, which owns Instagram and Facebook, said that 30 million new Threaders have already signed on. And it appears that far more people have signed up since. Each user’s Instagram account displays their membership number on Threads. Based on screenshots posted by new members, about 55 million people were signed up as of Friday morning. (Within hours of the launch, a Twitter attorney sent a letter to Zuckerberg warning of possible legal action and claiming that Threads had engaged in “systematic, willful and unlawful misappropriation of Twitter’s trade secrets.”)

Twitter hasn’t released its own membership numbers since last summer. But according to data research company Statista, Twitter had about 368 million users worldwide in 2022. So, Threads has attracted roughly 15 percent as many users as Twitter in just two days.

If you’re planning to join them, here’s what to expect.

For now, Threads is for use only on Apple or Android smartphones, and you must be an Instagram member to use it. If you’re already on Instagram, downloading and launching the Threads app takes only a minute. You’ll be urged to start following all the people you already follow on Instagram.

You’ll see messages — let’s call them threads — from the people you follow, and from those you don’t. An algorithm that’s familiar with your previous activity on Instagram will show you the threads it thinks you’ll want to see. The more you use both apps, the more accurate the algorithm will become.

But at present, Threads doesn’t give users the option of seeing only posts from the people they choose to follow. You can’t use hashtags to easily search for posts on specific topics. Also, there’s nothing like Twitter’s Lists, where you can create groups of fellow users with shared interests and communicate only with them. And there’s no sign of anything like Google Spaces, the audio chat feature that hosts conversations in real time.

When you’re ready to start posting your own threads, you’ll get a maximum message length of 500 characters. Also, you can add photos and videos up to five minutes long. But there’s no option for sending direct messages to specific people.

As of now, there are no ads to be seen. But that’s bound to change; this is all about making money, after all. That means that, like other social media sites, Threads will scoop up every bit of data you’re willing to share with it.

Over time, Threads will add more features like direct messaging and support for hashtags. But the company also promises to build “federation” into the new service. That’s the idea of a standardized system that would let people share their social media accounts among multiple networks. Just as you can move your phone service from T-Mobile to AT&T without having to change your number, a federated social network would let you easily transfer your Threads account to a rival service, or use both services at the same time.

That might be good news for Mastodon, another Twitter wannabe and one of the few social networks to embrace a federated model. The number of Mastodon users grew to 2.5 million after Elon Musk acquired Twitter last year and disgruntled users fled. But since then, the network has been moribund. If Threads follows through on its federation plan, it might offer Mastodon one more chance.