After 17 years with an iconic blue bird that came to symbolize the broadcasting of ideas to the world, billionaire Elon Musk renamed Twitter as X and unveiled a new logo, marking a focus on building an "everything app."

On Monday, a stylized white X on a black background became the new logo on Twitter's website, though the blue bird was still seen on the mobile app.

Since taking over Twitter in October, Musk has said he envisions an app that could offer a variety of services to users beyond social media, such as peer-to-peer payments, an idea that mirrors the widely popular WeChat app in China.

The transformation is more simply a way for Musk to make his mark on the company, said Tom Morton, global chief strategy officer at ad agency R/GA. "Twitter's changing name and logo has nothing to do with user, advertiser or market issues. It's a symbol that Twitter is Elon Musk's personal property.

"He conquered the castle, now he's flying his own flag."

The new logo garnered mixed reactions from users and sparked confusion about what tweets would now be called, while marketing and branding experts said the rebrand risked throwing away years of Twitter's name recognition.

"Only a few brands have become verbs or seen themselves referred to in global news outlets as often as Twitter has," said Matt Rhodes, strategy lead at creative agency House 337, which has worked with British telecom company Sky.

"Anything that makes it harder for people to find, or want to open the app on their cluttered phone screens risks harming usage," he said.

Fernando Machado, who previously held chief marketing officer roles at Activision Blizzard, Restaurant Brands International and Burger King, said rebrands typically take time to sink in, though "as a Twitter user, I confess that I miss the little bird already."

"Personally, I think the new approach feels a bit cold and impersonal," he said.

Outside Twitter's headquarters in San Francisco on Monday, police stopped construction workers from removing the Twitter sign, in a scene witnessed by a Reuters reporter. On one side of the building, only the blue bird and the letters "er" were left.

"#GoodbyeTwitter" was trending on the platform on Monday with reference to the old logo as some users criticized the new one.

Musk tweeted on Saturday that "soon we shall bid adieu to the Twitter brand and, gradually, all the birds."

'Everything app'

Musk has used the letter X repeatedly across his companies. He co-founded x.com as an online bank in 1999 which later transformed into PayPal. He bought the domain back from PayPal in 2017, saying it had "sentimental value."

The domain x.com now redirects to Twitter.

Linda Yaccarino, the former advertising chief at NBCUniversal who started as Twitter CEO on June 5, told employees in a memo on Monday that X "will go even further to transform the global town square."

The company will work on new features in audio, video, messaging, payments and banking, according to the memo, which was seen by Reuters.

The platform will face challenges to reinvent its business.

Since Musk's takeover, the company has faced tumultuous times with layoffs, a sharp drop in advertisers and the meteoric rise of Threads, Meta's response to Twitter.

The rebrand indicates Musk has given up on any plans "to revive Twitter as a powerful stand-alone social network and simply considers the $44 billion spent on the network a sunk cost," said Niklas Myhr, a professor of marketing at Chapman University.

"The last few months have been tumultuous at Twitter, and I don't think a new brand is going to solve everything," Drew Benvie, CEO of social media consultancy Battenhall, said.

"This is less about reinventing Twitter, and more about building a brand around Elon Musk's empire, including SpaceX, where the X branding really connects a little more closely."