Like on Facebook. The ‘like’ button and its old, and for some longed for, star of favorites on Twitter, the hearts of Instagram or TikTok… The same functionality has become commonplace on the internet. Capable of feeding both egos and bank accounts, making a news or message go viral, or spreading a rumor or false news in the same way.
But, what was its origin? Facebook was not born with this button. In 2007, when the social network created by Mark Zuckerberg was barely 3 years old —and already had 30 million users—, we found the germ of ‘likes’. A function that would only have 26 lines of code but would change everything. Until then, on Facebook, like on forums or other social networks, the only possibility of interaction was to comment on other people’s posts. The arrival of ‘likes’ would trigger the use of the platform and also the way in which Facebook could measure our interests internally.
A paradigm shift that, a decade later, would be the basis on which ad segmentation would grow, the knowledge of its users and, also, some of the biggest scandals of current Meta.
The woman who invented the ‘like’
Leah Pearlman was then one of the three product managers at Facebook, and she saw that something was wrong. The most popular posts were getting long threads of comments, many of them one or two words long (like “great” or “congrats”), with no way to locate the most interesting ones in a sea of noise. It might not sound like a big deal, but it bothered Pearlman and his coworkers, nearly all of whom were in their 20s and active Facebook users.
To Pearlman, the comment threads seemed like something you’d see on MySpace, Facebook’s more established rival at the time.
She and other Facebook workers, including engineering directors Akhil Wable and Andrew Bosworth, designer Justin Rosenstein and internal communications director Ezra Callahan, set out to create a universal and easy way to express approval on the social network. The code name of the project was “Props”, that is, accessories.
Pearlman, the creator of the ‘like’, ended up leaving Facebook and leaving the software world to create her own comic book publisher.
As you imagine, that ended up becoming the iconic button with the thumbs up. His story has now been recovered in the book “You Are Not Expected to Understand This”: How 26 Lines of Code Changed the Worldby Torie Bosch, which includes the ideas and comings of that idea and the reflections —and also regret— on the part of its creators.
The same virtues that made it an elegant front-end solution for a fast-growing software company in 2007—its simplicity, its ease of use, its universality, its desirability as a value metric—came to seem like vices when a platform in ruling line throughout the world applied it on a large social scale.
“I never expected what happened… We were working on other things that seemed much more important to us,” explains Pearlman, who would later retire from software, leave Facebook, and find a new working life by starting his own comic book publisher.
Facebook was not the first
But before the ‘like’ as we know it, other platforms tried similar methods. The now almost forgotten Digg thumbs up icon and Vimeo’s ‘Like’ button were some of the few precursors.
At the time, the main ranking factor was the number of comments, and ‘likes’ changed everything.
Pearlman called the Facebook button initially awesome (“awesome”), and got enough votes from his coworkers to fuel a hackathon, an all-night code development session where engineers and designers prototype potential new features. On July 17, 2007, a team consisting of Bosworth, Rebekah Cox, Ola Okelola, Rosenstein, and Tom Whitnah created the first button, according to a detailed account Bosworth posted on the question-and-answer site Quora in 2010. It was well received and it was given the green light for implementation.
They soon saw different uses for it. The advertising team thought that it could serve to show better ads to users. The platform team thought it could be used to filter posts with low interest. The news team, led by Bosworth, thought it could help them decide which posts to display in user notifications. At the time, the main ranking factor was the number of comments, and ‘likes’ changed everything.
After several delays, the team introduced the button Awesome to Mark Zuckerberg for final approval in November 2007. Zuckerberg turned it down. According to Bosworth’s account, Zuckerberg saw potential conflicts with Facebook’s privacy defaults (would likes be public or private?), a future ad platform (the ill-conceived and ill-fated Facebook Beacon), and the share button. that I was working on and that would also be implemented. He also disagreed on the name, preferring “like” to “awesome”. That is what would remain.
Mark Zuckerberg initially rejected the ‘like’ button
There were also internal discussions about whether the ‘like’ button would make users less reflective and lead to less pure interaction, which clearly seems to have happened. But it’s not clear that anyone at Facebook then worked on the assumption that their product design decisions would have such huge implications. Rather, they were focused on building a better and more attractive product than MySpace.
What finally pushed the ‘Like’ button forward was the weight of data. In a test, Facebook data analysts found that popular posts with the button elicited more interactions than those without. In February 2009, Zuckerberg had already approved the final version of the button, designed by Soleio Cuervo, a Facebook designer at the time, who drew it in Photoshop like the thumbs up we all know.

But applying code to the button involved much more than drawing it. Each “like” had to be stored in databases that linked it both to the post and to the person doing it. Much of the programming was carried out by engineer Jonathan Pines, with the help of another engineer, Tom Whitnah, and product manager, Jared Morgenstern. In the end, it was solved with 26 lines of code.
On February 9, 2009, Pearlman announced the launch of the ‘Like’ button with a note on the Facebook blog titled, precisely, ‘Like’. The button was an immediate success, and it didn’t take long for Facebook to find a way to integrate it not only on its platform, but also on the internet. The following year, both comments and posts could be liked.
‘Likes’: a tracking radar for Facebook ads

The button also became the default way to follow publishers and brands on Facebook, and when you did, Facebook used your “Like” to advertise those same pages to your friends. In April 2010, Facebook introduced a series of Like button plugins or widgets that allowed users to ‘Like’ pages outside of Facebook itself.
Those widgets became a source of ad trackingwhich reported to Facebook each time a logged-in user visited a site with a button, so that Facebook could use that information to target ads.

The “Like” button quickly became something much bigger than its creators had imagined. The “likes” became expressions of taste and identity. They became the driving force behind an increasingly powerful and complex news ranking algorithm: the more likes a post got, the more people would see it on Facebook. They became an asset for brands and advertisers, a norm that marked the success of a publication, the obsession of teenagers and influencers on social networks… And an immense source of data that would also generate the big scandals on Facebook.
Over time, Twitter would change its favorite, with a star, for a heart that also marked “likes” in 2015. Instagram would also end up assimilating it to the heart, and from there until now, becoming an information vector for online advertising and user tracking.
Everything, under the harmless gesture of a thumbs up.