Sarah Ferguson has branded much of social media a "sewer line".
The Duchess of York has penned an open letter as part of HELLO! Magazine's #HelloToKindness campaign about the positive and negative impact apps such as Twitter and Instagram can have on society.
The 59-year-old television personality - who was previously married to Prince Andrew, The Duke of York, with whom she has daughters Princess Beatrice, 30, and Princess Eugenie, 28 - has admitted that whilst it's a "force of good" for young people to have access to information at the click of a button and express their opinions online, it's important that people think before they post anything.
She wrote: "IN so many ways, the internet has been a force for good.
It enables us to keep in touch with friends and family all across the world.
"Our children can access the sum total of human knowledge at the touch of a button, wherever they are.
And social media means anyone can have a public platform to express their views, keep in touch with whatever sort of news they are interested in and develop relationships that would never have been possible before."
Sarah says that many parents are worried about how much time their children are spending online and called on them and everyone else to "confront" the issue "head on".
She continued: "Many parents worry, however, about how much time their children spend online.
"This generation of children has been dubbed 'the phigitals', because they are the first to draw no real distinction between the physical and the digital worlds.
"On average, children are spending nearly five hours a day in front of a screen - not much less than adults who typically clock up six hours gazing at smartphones, tablets and work computers.
That means we need to pay more attention than ever to what we're all being exposed to online.
"It's time to confront head on the fact that much of social media has become a sewer. "
The author also confessed that social media "terrifies" her and that she doesn't read any of the comments on her posts because she is aware there are trolls out there.
She added: "I'm on Twitter and Instagram, and I'm grateful for the fact that they allow me to communicate directly with people who are interested, promote my charitable causes and let people read my own words rather than someone else's slant on them.
"But the truth is, a lot about these sites terrifies me.
"I rarely if ever go 'below the line' on social media or news websites and read people's comments.
"I know that a lot say nice things, but there's a large minority who seem to think that all the normal rules of society don't apply to the internet.
"Take a look at any website, and you'll see extraordinarily abusive comments aimed not only at people in the public eye but also other internet users.
"Bullying, sniping, bitching, even the most appalling sexism, racism and homophobia are commonplace - it seems that online, anything goes."
Sarah joins the likes of David and Victoria Beckham, Ronan and Storm Keating and Liam Payne in offering their support via the hashtag #HelloToKindness, and the initiative has now been tabled in Parliament.
HELLO! states that: "An early day motion put forward by Layla Moran, Liberal Democrat MP for Oxford West and Abingdon, requests the House of Commons to support HELLO! magazine's #HelloToKindness campaign and praises the campaign for supporting kindness in an effort to combat the growing problem of online abuse."
Layla met with the publication's Editor-in-Chief Rosie Nixon and is "fully behind" the campaign, adding: "A little kindness is needed everywhere right now."
The motion "congratulates the campaign for standing up to abuse that occurs on social media platforms in an attempt to promote a more positive, welcoming environment online, commends the campaign for garnering large public and celebrity support in calling for less abuse and more kindness online; and calls on the Government to work with social media companies, schools and civil society to further the aims of campaigns like #HelloToKindness".
View Sarah Ferguson's full letter here: www.hellomagazine.com/healthandbeauty/health-and-fitness/2019021167679/sarah-ferguson-online-bullying-hello-to-kindness-exclusive