For many years, Facebook's ‘thumbs up’ icon adorned the sign that greeted visitors to the company’s Californian headquarters.
It was an image, of course, of the Like button, which was launched in 2009. It was eventually replaced at Mark Zuckerberg's main office in 2021 by the blue pretzel logo of Meta. By then, however, it was already clear that the ubiquitous, blue-cuffed fist already become one of the most significant pieces of computer code ever released, shifting the goalposts in how the world consumes information, markets products and communicates.
Today, 20 years after Facebook was launched on 4 February 2004, there are countless Likes every day, including everything from personal photos to news pieces to viral posts (especially viral posts).
The Like - and its ability to turn media into a popularity contest - has powered most of the social media giants launched in its wake, as well as helping drive whole sections of the economy, such as influencer marketing. But it has also been at the centre of rows over privacy and blamed, in part, for the rise of highly polarised and distorted content online, 'fake news' and filter bubbles.
On its anniversary, Yahoo News takes a look at the Like that Zuckerberg built.
Why ‘Like’ almost didn’t happen
Facebook wasn't the first site to employ a button that allowed users to indicate approval. The social news site Digg, for example, had a way to ‘Digg’ or ‘Bury’ news stories, but Facebook’s Like eclipsed these due to its versatility and scale - you could like everything from a friend’s photo to a local business.
At Facebook, the iconic button nearly didn't make it into the real world, with workers at the company believing it was a ‘cursed project’ due to rejections from Mark Zuckerberg.
Writing on question-and-answer site Quora, Facebook engineer Andrew ‘Boz’ Bosworth described one 2007 meeting where Zuckerberg turned down the feature. He wrote: "Ready to launch and things appear to be all set but final review with Zuck surprisingly doesn't go well. Concerns about whether the interaction is public or private, cannibalising from the share feature."
Bosworth also recalled how the project, initially codenamed 'Props', debated using a plus sign or stars, before settling on the thumbs up in 2007 after it was finally given internal approval.
The button was first known as the Awesome button and tested in people's NewsFeed, initially with a system both for positive and negative feedback.
Before it was adopted, the team had to prove that using a Like button didn't reduce the number of comments, which were the currency of popularity on Facebook at the time. In tests, the team found that having a Like button actually increased comments.
In a blog post as it launched, Facebook said: "We've just introduced an easy way to tell friends that you like what they're sharing on Facebook with one easy click. Wherever you can add a comment on your friends' content, you'll also have the option to click 'Like' to tell your friends exactly that: 'I like this.'"
How Like changed the world
The Like button rapidly grew to become central to Facebook, dictating (among other things) which stories a visitor to the News Feed would see.
As Facebook put it: "When you like something, this lets us know to show you other content that we think you’d also like to see."
That ‘Like’ helped drive a huge change in the media landscape, with posters incentivised to chase Likes (other, more complex, ‘reactions’ such as a sad face and a love button were added many years later).
The more Likes a post got, the more it would be seen by other people, so users and media outlets rapidly learned to alter their output to harvest more and more of them.
Ezra Callahan, one of the first dozen or so employees at Facebook, told Fast Company that some at the company had worried the Like button was too easy, and that it would "eliminate thoughtful engagement, because people were lazy and would take the lazy way out".
Facebook turns 20 - read more
But the momentum was unstoppable. Likes powered a new news-feed ranking algorithm; helped drive advertising; and allowed Facebook to gather data on users' habits. Every subsequent rival, from Twitter to TikTok, has since relied on Likes or a similar mechanism to drive the algorithm that feeds people content.
And it is unlikely to change too much in the near future with three of the most popular sites used by younger people to consume content - Instagram, TikTok and YouTube - all in part driven by technologies similar to Facebook’s ‘Like’ button.
The dark side of Likes
Facebook's Like button has led to an information economy where users become addicted to refreshing their screens - in the same way as gamblers become addicted to slot machines.
The 'Like' button informs what users see on screen, and also rewards them for posting content which strikes a chord with others.
Professor Daniel Kruger of the University of Michigan suggested that apps like Facebook aim to be 'as addictive as possible' and affect the same brain regions as cocaine - and that helps explain one of the key reasons that Facebook has become so entrenched in our lives: we can’t put it down.
Behavioural psychologist, Nir Eyal, the author of Hooked: How to Build Habit-Forming Products told the Guardian in 2018, that such products are designed to be addictive.
Eyal said: “It starts with a trigger, an action, a reward and then an investment and its through successive cycles, through these hooks, that habits are formed. We see them in all sorts of products, certainly in social media and gambling. This is a big part of how habits are changed.”
“The products are built to be engaging and what’s engaging for some is addictive for others, that’s clear.”
There are also increasing concerns over Facebook (and social media more generally) and its impact on mental health. Analysis of early users of Facebook (when it was restricted to U.S. universities) found that it led to an increase in severe depression by 7% and anxiety disorder by 20%.
A 2018 study by University of Queensland researchers found that taking a short, five-day break from Zuckerberg’s app actually reduced levels of stress hormone cortisol.
Howver, after five days, most of the 138 volunteers actually reported a drop in feelings of well-being - and were looking forward to getting back on Facebook.
The impact of the Like button has also been tied to significant political moments, too.
Facebook's algorithms were used to impact general elections in the Philippines in 2015, in the UK's Brexit vote and the US Presidential election in 2016.
In 2014, employees of Cambridge Analytica acquired the private data of tens of millions of Facebook users to build profiles of voters. The data of 87 million users had been collected by an innocent-looking app, and was used to target political ads.
Facebook 'Likes' were key to this, allowing political groups to build complex psychological profiles for targeted ads. Just a few 'Likes' were enough to build profiles showing a person's sex, who they will vote for, and predict their vulnerability to substance abuse.
What does the future hold?
Social media expert Elisah van Allen, Head of Social Media at specialist communications agency 33Seconds, says that the Like button created whole economies such as the rise of social media influencers - but also has a dark side in terms of impact on people’s mental health.
Van Allen tells Yahoo News UK: "The FB 'Like' button has changed how we connect with individuals, brands and businesses. It lets people validate each other's ideas, achievements, moments etc. quickly and easily, which creates positive reinforcement and encourages more meaningful interactions online.
The 'Like' button has also shaped online algorithms, influencing the content we see and the connections we make. Its impact on user engagement and content visibility has paved the way for influencers, content creators and brands to succeed online, leveraging it as a recognised metric of popularity and relevance.
But the negative side is also very visible in today’s world, Van Allen says - in everything from the pressure to find approval online, to low-grade content produced to garner reactions.
The changed media landscape created by the Like button has been blamed for everything from the rapid spread of fake news, which goes viral when users Like and share anything that agrees with their world view, to ‘filter bubbles’, where algorithms ‘learn’ user preferences and feed them a distorted media landscape with only one side of the argument.
Van Allen says: "On the media and publishing side of things, it could be argued that the 'Like' button has over time had an impact on the type of news content we consume and the way in which we react to it - for example, influencing certain publications towards producing purposefully polarising content, in order to elicit an immediate emotional response from readers."
"Likes could potentially be damaging to our mental health and the validation-seeking behaviour it may induce. Striking the right balance between fostering a positive online environment and addressing the potential pitfalls of social validation is a challenge we can't ignore and should continue to be discussed; especially for younger generations now growing up with social media in their lives."