US TikTok ban: When and why could the app be outlawed?
TikTok is beginning its case against a law which will ban it in the US unless it is sold by ByteDance, its Chinese parent company.
The video sharing app has millions of users worldwide, but has faced questions over the security of data and links to the government in Beijing.
Who wants to ban TikTok in the US and why?
Lawmakers from both major US political parties supported a law that bans TikTok unless ByteDance agrees to sell to a non-Chinese company.
They fear the Chinese government could force ByteDance to hand over data about TikTok's 170 million US users.
TikTok insists it would not provide foreign user data to the Chinese government.
In April, following approval by Congress, President Joe Biden signed a bill paving the way for TikTok's forced sale.
Previous attempts to block the app in the US on national security grounds have failed.
Former US President Donald Trump tried to ban the app when he was in the White House in 2020.
But Mr Trump - the Republican 2024 presidential candidate - has criticised the new legislation, arguing that limiting TikTok would unfairly benefit Facebook.
Vice President Kamala Harris, who is running against Mr Trump as the Democrat candidate, has used TikTok and popular social media trends like Charli XCX's "brat" to try and win over young voters.
A spokesperson for her campaign has previously said they would "just like to see a change in ownership" of TikTok rather than its ban.
When could TikTok be banned?
Mr Biden signing the bill into law did not mean an immediate US ban for TikTok, but it did start a ticking clock.
The legislation gives ByteDance nine months to sell TikTok to a new buyer, with an additional three-month grace period, before any ban would take effect.
TikTok said this could mean it is either forced to sell or shut down in the US by 19 January 2025, after the US presidential election in November.
But the company's fight against the legislation in court, which began when it sued to block the law in May, could take years.
How would a TikTok ban work?
The most straightforward way for the US to ban TikTok would be to remove it from app stores, such as those operated by Apple and Google for iOS and Android devices.
App stores are how most people download apps on to their smartphones and tablets, so the ban would stop new users from getting TikTok.
It would also mean that people who already had the app would no longer be able to get future updates designed to improve security or fix bugs.
The bill forbids applications controlled by US adversary countries from being updated and maintained in the US.
It gives broad powers to the president to limit apps with ties to Russia, China, Iran and North Korea.
What has TikTok said it will do about the ban?
Arguments in TikTok's appeal begin in a Washington DC court on Monday 16 September and will be heard by a three-judge panel.
A group of TikTok creators who oppose the law over concerns about its impact on their work will also make their case at the hearing.
TikTok has previously called the legislation an "unconstitutional ban" and affront to the US right to free speech.
"We are confident and we will keep fighting for your rights in the courts," said TikTok boss Shou Zi Chew. "Rest assured," he told users in a video, "we aren't going anywhere".
He previously said the bill would give its social media rivals more power and put thousands of American jobs at risk.
ByteDance would also have to seek approval from Chinese officials to sell TikTok, but Beijing has vowed to oppose such a move.
How have TikTok users in the US responded?
Many US creators and users have criticised the potential ban.
Tiffany Yu, a young disability advocate from Los Angeles, told the BBC at a protest outside the White House the platform was vital to her work.
In March 2024, TikTok asked its 170 million US users to contact their political representatives and ask them not to support the bill.
But the deluge of "confused" calls from TikTok users to congressmen and senators seemingly backfired.
Several politicians said the campaign worsened the concerns they had about the app, and strengthened their resolve to pass the legislation.
Is TikTok banned in other countries?
It is thought the US TikTok bill could inspire similar moves elsewhere.
TikTok is already banned in India, which was one of the app's largest markets before it was outlawed in June 2020.
It is also blocked in Iran, Nepal, Afghanistan and Somalia.
The UK government and Parliament banned TikTok from staff work devices in 2023, as has the European Commission.
The BBC also advised staff to delete TikTok from corporate phones because of security fears.
How does TikTok work and how much user data does it collect?
At the heart of TikTok is its algorithm, a set of instructions which determines which content is presented to users, based on data about how they engaged with previous material.
Users are offered three main feeds on their app - Following, Friends and For You.
The Following and Friends feeds present users with content from people they have chosen to follow and who follow them back, but the For You feed is automatically generated by the app.
This curated feed has become the main destination for users looking for new content, and creators hungry for the millions of views TikTok videos can clock up if they go viral.
Critics say the app collects more data than other social media platforms in order to power its highly personalised system.
This can include information about users' location, device, the content they engage with and keystroke rhythms they exhibit while typing.
But popular social media apps such as Facebook and Instagram collect similar data from users.
