Ten years ago, a 29-year-old entrepreneur named Jack Dorsey typed five words - "just setting up my twttr" - into a website and pressed send. It was a fairly mundane debut for Twitter, which would go on to become one of the world's hottest internet companies.
But Dorsey was hardly to know that. His previous start-ups had included a service to dispatch taxis and ambulances over the internet and a way to connect medical devices. So twttr (as it would be known until its founders shrugged off their disdain for vowels six months later) was by no means a guaranteed success.
In the intervening years, the microblogging service has become an integral feature of millions of lives. It is the broadcast medium of choice for celebrities; it has built (and ruined) careers; and it is where news breaks before anywhere else.
For better or for worse, the service is closely associated with major events and cultural movements, including the Bring Back Our Girls campaign, the Arab Spring, the Black Lives Matter movement and Barack Obama's 2008 grassroots ascendance to the White House.
And for nine of Twitter's 10 years, it was the darling of the technology world.
But the past 12 months have not been kind to Twitter. At the time of its IPO on the New York Stock Exchange in 2013, analysts feverishly predicted that Twitter could ride the same trends that had made Facebook a $100 billion internet powerhouse with a population larger than any country. But two-and-a-half years later, Twitter's user base is a fifth the size of Facebook's and has essentially stopped growing.
In New Zealand, there are more than 370,000 Twitter users - about 7 per cent of the population, though the bulk is made up of 15-24-year-olds.
Despite the service's apparent simplicity - write a message of up to 140 characters and publish it, and follow people to see their tweets - a hidden complexity means new users often find Twitter baffling. The service's unwritten rules of engagement, the work new users have to put into following the right people, and the frantic nature of Twitter's real-time feed can be confusing.
Last year, the company returned to the past by replacing its chief executive of five years, Dick Costolo, with Twitter's visionary founder, six years after Dorsey had himself been removed.
The new leader has cut jobs, presided over a management exodus and reconsidered the fundamental and much-loved features that have served Twitter for the past decade. Last month, the service began showing users tweets arranged by an algorithm, rather than the simple chronological feed people are used to. Reports of a plan to extend the 140-character limit, meanwhile, were quashed last week. Dorsey has so far failed to bring about the Steve Jobs-esque revival in Twitter's fortunes that was hoped for, at least when it comes to the number of people using the service.
However, Dara Nasr, Twitter UK's managing director, says Dorsey has had a hugely positive effect.
"I'm more excited about Twitter than I ever was before and a lot of that is due to Jack and his vision," Nasr says. "What he's done is recognised there need to be changes.
"He's been very clear to investors that things need to change - they'll take time but there's a plan in place and that's resonated."
Twitter boasts pockets of growth around the globe but when it comes to the company as a whole, growth has been flat for six months, standing at around 320 million users.
But Nasr says Twitter still has a not-unimpressive reach, especially when you count the 800 million or so "logged-out users" - those who do not have accounts but might use the service anyway, or see tweets elsewhere on the internet.
"It's not a small figure, it's very much a global product, but yes of course we'd like to grow. What we want to do is show the respect and love we have for our existing 320 million users and also open the door for other users," says Nasr.
He points out that Twitter is busier than ever: when Leonardo DiCaprio finally won an Oscar in February, there were 440,000 tweets a minute, a record for the service.
New Zealand's most followed user is singer Lorde. Others among the most popular here are UK-based DJ Zane Lowe, Dan Carter, Kim Dotcom and Rhys Darby.
Last week, Kim Kardashian, one of the world's biggest internet celebrities, said Twitter was "where I can freely talk and have conversations with anyone and everyone".
But many users, those more partial to privacy, are less enamoured. Twitter's public nature, the ability to hide behind a pseudonym and its free speech ethos have made trolling an immense problem.
Nasr says the majority of tweets are not problematic, but that "if you were to hold a mirror up to society, society's not necessarily lovely".
He adds that "we couldn't take it more seriously than we do" and promises Twitter will do more to combat trolling.
Dorsey has outlined several other major priorities for Twitter, including the growth of Periscope, an app that allows smartphone owners to broadcast live video (one of Periscope's more unlikely successes was in January, when 20,000 people tuned in to watch a live video of pedestrians trying to jump over a puddle in Newcastle).
Although the decline in Twitter's share price has levelled off in recent weeks, bringing a semblance of stability to the company, the man whose five-word message began a huge social phenomenon has made it clear that massive changes are in the offing.
When most companies enter their second decade, their most volatile days tend to be behind them. But for Twitter, the biggest tests could still lie ahead.The Daily Telegraph