Twitter has announced a dramatic product change, saying it will recast the way it displays tweets on its homepage by customising them to individual users, instead of displaying tweets in reverse chronological order.
The change to the timeline will appeal to advertisers by giving more prominence to tweets that advertisers pay for to promote products.
The change comes just hours before Twitter reports fourth-quarter earnings to investors, who have been pressuring the company to increase user growth and ad revenue by making the product easier to use.
Reports that Twitter could be changing the timeline surfaced last week, prompting laments by users tweeting with the hashtag #RIPTwitter.
They said using a customised, or algorithmic, timeline - similar to Facebook's News Feed - meant Twitter would lose one of its signature features.
The move to have tweets paid for by advertisers surface higher in individuals' timelines is expected to make it more likely users will respond to ads.
In testing the new timeline, Twitter wrote in a blog post that it saw increased user interaction with ads and tweets about live events. Advertisers have said their ads can get lost in the reverse-chronological timeline.
Twitter said it analysed how users have engaged with billions of tweets to determine what they are most interested in.
When users open their timeline, they will see several tweets from the past several hours that Twitter thinks they are most likely to interact with. Underneath it they will see the traditional reverse-chronological timeline.
Users can choose to opt out of the new algorithmic timeline.
Jack Dorsey, Twitter's chief executive and co-founder, tried to reassure users in a series of tweets last week that Twitter would remain the place for live news and commentary.
"Twitter is real-time. Twitter is about who & what you follow. And Twitter is here to stay! By becoming more Twitter-y," Dorsey wrote. "We're going to continue to refine it to make Twitter feel more, not less, live!"