Twitter's paid blue tick re-launches after pause
Twitter's paid-for verification feature is rolling out once again on Monday. It was paused last month after being swamped by impersonators.
It is still $8 per month - but there is now an increased fee of $11 for those using the Twitter app on Apple devices.
Twitter's owner Elon Musk has previously said in tweets that he resents the commission fee Apple charges on in-app purchases.
Twitter Blue's additional features include an edit button.
This has long been a feature requested by many Twitter users, although there are others who argue that it increases the potential for the spread of disinformation, if a tweet is altered after being widely shared.
Blue-tick subscribers will also see fewer ads, have their tweets amplified above others, and be able to post and view longer, better quality videos, the platform says.
Previously a blue tick was used as verification tool for high-profile accounts as a badge of authenticity. It was given out by Twitter for free - but only the firm itself decided who got one.
Mr Musk argues that this was unfair.
Those who had a blue tick under the previous regime currently still have them, but now some of these users also have a message which appears if the tick is pressed saying the account is a "legacy verified account" and "may or may not be notable".
However, those check marks will now eventually be replaced with either gold (for businesses) or grey (for others such as authorities) badges, according to Twitter's own account.
Under the new system, subscribers who change their names or display photos will lose their blue tick until the account has been reviewed by Twitter.
The service had a chaotic initial launch in November, when people started impersonating big brands and celebrities and paying for the blue-tick badge in order to make them look authentic.
Many pretended to be Elon Musk himself.
In one instance, a user claiming to be the US pharmaceutical firm Eli Lilly tweeted "insulin is free", causing the real firm's share price to tumble - however, Eli Lilly has since agreed that insulin prices could indeed be lower.
Having said that, anecdotally, quite a few accounts appeared to take the opportunity to subscribe for legitimate reasons.
Elon Musk has made a number of sweeping changes since he took over Twitter at the end of October after buying it for $44bn (£38bn).
He said the firm was operating at a loss of $4m per day, and that it needed to become profitable.
He has laid-off around half its workforce, introduced bedrooms at Twitter HQ in San Francisco for the remaining staff working long hours, and begun re-instating controversial banned accounts, including the rapper Ye (Kanye West), former US president Donald Trump and influencer Andrew Tate.
Mr Musk also says Twitter accounts which have been inactive for a certain period of time will be deleted. This has caused dismay among those who say they cherish the accounts of loved ones who have died.
Film director Rod Lurie tweeted that his "heart was broken" at the thought of the account of his late son, Hunter, disappearing.
Unlike Facebook, Twitter users cannot nominate someone to take control of their account after their death although state executors can contact the firm with requests.
You can follow Zoe Kleinman on Twitter @zsk.