Harold was delighted. He had been worried that some of the anonymous messages he got via his new app app would be very rude. But, he says, "it was actually a warm flood of responses about people's experiences with me, so it was a really nice surprise".

Harold is one of more than 15 million people around the world who have downloaded NGL. The app invites anonymous questions and comments from followers.

"It's fun," Harold explains. "Who wouldn't want to know someone's secret thoughts on them?"

Not everyone agrees. Reggie Baril, a Los Angeles musician, got messages with "more hate than not". One of them called him "a social climber".

Online anonymity is a big issue. Critics say it allows people to say hurtful things that they could not get away with if everyone knew who they were.

According to Valeriya Safranova of the New York Times, anonymous messaging apps are usually withdrawn because of "unfettered bullying, harassment or misinformation."

Premier League players have received thousands of abusive messages. One survey found that 56% of these were racist.

As a result, some people want all social-media users to sign in with verifiable identification. This would make them easy to trace if they broke the law.

But for others anonymity is highly attractive. Being able to confess feelings that you have always kept quiet about can be a huge relief.

Anonymity can also keep you safe. Without it, according to Amnesty InternationalAn international non-governmental organisation focused on human rights. , many people would be at risk, such as anti-government campaigners and journalists who uncover corruption

In countries like Russia and China, VPNs have been banned to stop users hiding their identities.

Yes: As things stand, anyone can post appalling abuse on the internet, or pretend to be someone they are not for grooming or other criminal purposes. Compulsory ID would put an end to that.

No: It would spell the end of freedom of speech online. Many people would no longer dare say what they feel or express political opinions, for fear of being persecuted or thrown into prison.

Or... All social-media platforms should give users a choice about receiving messages from people they do not know. Sensible people know that using an app like NGL is asking for trouble.