It was often likened to a global town square.
While that analogy may have been overplayed, Twitter evolved into something roughly fitting that description after its public debut two decades ago, on July 15, 2006.
At the height of its influence, the platform — renamed X in 2023 — gave the powerful and the unsung alike a place to preen and pontificate, 140 characters (later 280 characters) at a time.
Its memes and viral videos distracted and entertained, but Twitter also became the preferred way for governors and heads of state — and one American president in particular — to communicate with the public. Protesters, as in Iran after a disputed election in 2009, used it to get their message out to the wider world. And women shared frank accounts of sexual harassment and assault, fueling the #MeToo movement.
Here are some highlights (and a few lowlights) from the last 20 years:
July 2006
A Tweet is Born
On July 15, 2006, a new era of provocative hot takes, kneejerk reactions and random thoughts on social media ushered itself in with the public debut of Twitter.
A soft launch had preceded that milestone about four months earlier, when Jack Dorsey, Twitter’s co-founder and its first chief executive, composed the very first tweet. At the time, the platform’s name varied slightly from its ubiquitous moniker.
“just setting up my twttr,” Mr. Dorsey wrote on March 21, 2006.
2009
The Birth of ‘Black Twitter’
Among the earlier popular hashtags — a workaround for Twitter’s search function — was #uknowurblackwhen, coined by the user Ashley Weatherspoon. The New York Times critic James Poniewozik called that tag “a sort of origin story for Black Twitter,” which he described as “general phenomenon of Blackness and Black culture manifesting online.”
There were reaction emojis (a GIF of Michael Jackson eating popcorn from the “Thriller” video as a shorthand for amused anticipation) and plenty of jokes, often with an underlying purpose or statement (the tag #OscarsSoWhite was a protest against a lack of diversity in Hollywood in awards season.)
Eventually, Black Twitter would take on the killings of Trayvon Martin and George Floyd and the Black Lives Matter movement; President Trump’s election; BBQ Becky and Permit Patty; and Elon Musk’s acquisition the platform.
May 2009
A Dispatch From Space
Yuri Gagarin was the first person in space. Neil Armstrong was first to set foot on the moon. So what about Mike Massimino?
Not all space pioneering feats are created equal, but Mr. Massimino, an American astronaut who in 2009 was part of the STS-125 shuttle mission to repair the Hubble Space Telescope, has his own historical footnote.
On May 13, 2009, he became the first person to tweet from space, emailing a dispatch to NASA that the space agency posted to his account.
“From orbit: Launch was awesome!!,” he wrote. “I am feeling great, working hard, & enjoying the magnificent views, the adventure of a lifetime has begun!”
June 2009
The Green Movement
A protest movement that would become known as the Green Movement arose in Tehran and other Iranian cities after a disputed presidential election. The protesters took to social media — Twitter, primarily — to transmit their message beyond Iran’s borders, but short bursts of text and brief video clips proved no match for Iran’s government, which violently suppressed the uprising.
c. 2012
Twitter Gets Weird
As Twitter became increasingly defined by its subcultures, “Weird Twitter” emerged as a term to describe a stream-of-consciousness assortment of random observations, non sequiturs and nonsensical takes.
Some pandered for “likes” or to provoke a torrent of replies, the snarkier the better.
On Sept. 29, 2013, one of the main figures of Weird Twitter, @dril, posted an itemized list of expenses that included $200 for food, $150 for utilities, $800 for rent and $3,600 for candles. “someone who is good at the economy please help me budget this,” he wrote. “my family is dying.”
The “Candles tweet,” as it became known, was retweeted about 57,000 times and received more than 900 replies. When one user suggested that @dril “spend less on candles,” the response was swift and to the point: “no.”
March 2014
An Oscar-Worthy Selfie
It was an Oscar moment that brought Twitter to a crawl, but it was not an acceptance speech or red carpet look.
While hosting the 2014 Academy Awards, Ellen DeGeneres pulled out a Samsung phone for an impromptu selfie with a group of Hollywood A-listers in the audience.
There was Bradley Cooper, who was holding the phone, Meryl Streep, Jennifer Lawrence, Lupita Nyong’o, Brad Pitt, Julia Roberts and Kevin Spacey in the frame. The image was retweeted more than two million times during the show, setting a record at the time.
October 2017
The Rise of #MeToo
In the days after The Times published an investigative report detailing decades of sexual harassment allegations against the Hollywood producer Harvey Weinstein, women took to Twitter to express that they, too, had been victims of such misconduct. The movement that those posts fueled took its name from the hashtag appended to them: #MeToo.
The actress Alyssa Milano was credited with inspiring the online campaign with a post on Oct. 15, 2017 (though Tarana Burke had created the Me Too mantra a decade earlier to seek healing for Black women who had suffered sexual abuse). “If you’ve been sexually harassed or assaulted write ‘me too’ as a reply to this tweet,” Ms. Milano wrote.
2020
Rest in Tweet
In the evolution of the obituary, Twitter cemented its role, both as space to break news about notable deaths and for the cascade of tributes, large and small, that follow.
In August 2020, when the “Black Panther” star Chadwick Boseman died of colon cancer at 43, his Twitter account and other social media pages delivered word to his fans.
Mr. Boseman’s family posted that he had received a Stage 3 cancer diagnosis four years earlier. They shared that, as the disease worsened, he had been going through operations and chemotherapy while continuing to appear in many of his best-known movies.
“A true fighter, Chadwick persevered through it all, and brought you many of the films you have come to love so much,” his family wrote.
The post received more than 6.5 million likes and was retweeted more than 2.5 million times.
January 2021
A President Loses a Platform
Late-night fusillades, ALL-CAPS missives and schoolyard taunts.
No other American president has employed the communication style of Donald J. Trump, who amassed more than 88 million followers on Twitter during his first term in the White House.
But Mr. Trump’s spreading of falsehoods and impulsive streak cast him at odds with some social media companies, particularly Twitter, during the coronavirus pandemic and after his loss in the 2020 election.
As Covid-19 was marching across the globe in 2020, Mr. Trump retweeted a video that falsely suggested that the anti-malaria drug hydroxychloroquine was an effective treatment for the virus, a post that Twitter later took down.
The president’s standing with Twitter reached a low point on Jan. 8, 2021, two days after a mob of Mr. Trump’s supporters stormed the U.S. Capitol as part of an effort to stop Congress from certifying the election of Joseph R. Biden Jr. as president.
Twitter announced that it was permanently banning Mr. Trump from its service, citing two of Mr. Trump’s posts that it said violated its rules against glorifying violence. In one of the posts, Mr. Trump called his supporters “patriots,” while in another he said he would not attend Mr. Biden’s inauguration.
November 2022
X-Communicated No More
Mr. Trump sought to compensate for his banishment from Twitter and other social media sites by starting his own commentary platform in February 2022: Truth Social.
A few months later, the seeds were planted for Mr. Trump’s eventual return to Twitter when Mr. Musk, the world’s richest man and a staunch ally of Mr. Trump’s, struck a deal to buy Twitter for roughly $44 billion.
“I hope that even my worst critics remain on Twitter, because that is what free speech means,” Mr. Musk tweeted at the time.
In November 2022, Mr. Musk announced that he was reinstating Mr. Trump’s account after conducting a poll on Twitter.
December 2022
Braggadocio and a Zinger
With a single click of the powder-blue tweet button (the button for posting is now black), the famous and anonymous alike could name call, offend or carry on public feuds at a staccato pace.
Enter Andrew Tate and Greta Thunberg.
In December 2022, Mr. Tate, the online influencer who is currently facing human trafficking charges in two European countries, took a swipe at the environmental activism of Ms. Thunberg in a Twitter post.
“Hello @GretaThunberg,” he wrote. “I have 33 cars. My Bugatti has a w16 8.0L quad turbo.”
Mr. Tate, who, along with his brother, Tristan Tate, is known for misogynistic views and for flaunting his wealth, added that he would send Ms. Thunberg a list of his vehicles’ emissions.
Ms. Thunberg delivered a scorching comeback.
“Yes, please do enlighten me,” she responded, providing a fictitious email address that sought to diminish his manhood.
May 2023
A Glitchy Debut
As many prolific posters were souring on Twitter, or X, under Mr. Musk, one Republican with presidential aspirations and designs of supplanting Mr. Trump as the party’s standard-bearer was bullish about its potential for connecting with voters: Gov. Ron DeSantis of Florida.
On May 24, 2023, Mr. DeSantis chose to announce his presidential run with an audio livestream on X.
The production was marred by technical glitches, hot-mic moments and drowned-out and half-said conversations before the livestream abruptly cut out.
Rivals pounced on the miscues, including Mr. Trump.
“The DeSanctus TWITTER launch is a DISASTER!” Mr. Trump wrote on Truth Social, using one of his derisive nicknames for Mr. DeSantis.
2022-23
Bye Bye Birdie
After Mr. Musk assumed control of Twitter, which he renamed X in 2023, retiring the brand’s blue bird logo, a stream of left-leaning celebrities quit using the service. The defectors included Mark Hamill, Whoopi Goldberg, Shonda Rhimes and Barbra Streisand.
A number of them left for Bluesky, an experimental social media app that was started in 2019 under Mr. Dorsey, Twitter’s former chief executive.
