The NSPCC and Channel 4's teen drama Hollyoaks are tackling "sexting" - the sending of explicit texts, images and videos - in an ad campaign and in a new plot aired this week. The Duchess of Cambridge even addressed the issue at a charity conference.

Here is a selection of open-letters from parents who blog to their pre-teen or teenage children about the issue.

By Jean, a single parent to two teenage girls

Dear girls,

So, sexting. It's not something I ever imagined we'd have to talk about, mainly because it didn't even exist until a few years ago.

We've had plenty of conversations about sex over the years, and now you're both teenagers I never shy away from talking to you about alcohol and using drugs, but this is a new one and although you're probably cringing right now the fact it exists means we need to talk about it.

Children and technology 91% of UK children live in a household with access to the internet (2012) 62% of children aged 12-15 own a smartphone (2012) 43% of children use the internet in their bedroom (2012) 17.1 hours - the average number of hours 12-15-year-olds spend online each week (2012) Source: Threat Assessment of Child Sexual Exploitation and Abuse report (June 2013)

The biggest problem with sexting is the lack of control on your part. Once you send an explicit photo or video to someone, as soon as you press "send" you have handed over control to whoever receives it. Think that's not a problem because he's someone you trust? Maybe now, yes, but what about when you are no longer a couple/friends and he decides to share your photo?

Before long everyone you know (and plenty that you don't) will have seen that image, the one that was meant for one person's eyes only, and there's not a thing you can do about it. Once it's out there in the ether you can kiss goodbye to any control over who sees it. Pretty yucky, eh?

And just in case you're wondering, if you did get caught sexting, of course I'd be disappointed. Not because it would be embarrassing for me, although of course it would be. No, I'd be more upset about your lack of self-respect. Do you respect yourself enough not to be pressured or emotionally blackmailed into something like this? I think you do.

Think about it this way - before you send an intimate message or photo to anyone ask yourself if you would post it on your own Facebook wall. No? Then don't send it to anyone. End of.

Jean

Image caption Hollyoaks' Holly Cunningham shares a revealing photo which is posted online

By Tim Atkinson

Dear son,

This isn't an easy letter to write but it might just be one of the most important you read, so please read on. And I know what you're thinking - here goes dad spoiling the fun, being boring, not understanding anything.

But the thing is, I do. I understand what goes on and I understand why it happens, too. And I know a little of the consequences - enough to know that it isn't always just "fun". These things stick around. And in a few years from now, the things you say, the pictures you post, the texts and tweets and updates… well, they could all come crashing down around your head.

But dad, you're saying - it's harmless, it's a laugh, everyone does it.

Well just because everyone does, it doesn't make it right. And it might be a laugh now, but people change, relationships change. What's said can't be unsaid and if it's in writing then it's potential dynamite.

And it isn't always harmless. Anything but. What's done in the heat of the moment or the height of passion can be potentially devastating in the morning. And remember - these things have a habit of sticking around.

So before you dismiss it as harmful 'banter' just remember:

*Other people will see or read it. It's almost inevitable. Can you deal with that?

*It might come back to haunt you later. Friends can become enemies. Don't leave them with any powerful weapons to use against you.

*And finally - respect the person you're with. And ask yourself whether what you're saying or what you're doing shows that.

Simple rules but I think they'll make things a lot less complicated for you down the line.

Love,

Dad

By Jo Middleton

Dear daughter,

I want you to take a few minutes please just to picture a little scenario.

It's been three years in the making but you are finally applying for your very first job out of university. (It will come round quick you know.) It's exactly what you want - the first step on a dream career path - and you've been offered an interview. You're over the moon of course, and so you should be, you've worked hard to get here.

You spend ages preparing and are feeling confident. You rock up, in your best black suit and the smart shoes you borrowed from your flatmate, and prepare to be grilled. The panel look frosty though, concerned. "We've been researching you online," they say, "and we found this…"

More from the Magazine Emily Cook - speaking to the BBC News Magazine about self-taken photos or "selfies", says that her generation has forever been warned about internet risks and, as a result, she's careful. "At the end of the day it's my face and body, and if I choose to put it online that's up to me, but I also have to take the blame if they fall into the wrong hands. I'd never post anything I wouldn't want printed and sent to my mum." A history of the selfie

Bam.

That's it, dream job out the window.

I know you probably think I'm just some cynical old technophobe, that I'm uncool and don't understand young people, but the problem is that I understand young people and technology only too well. Sending that provocative picture of yourself, that suggestive text message, might feel like a perfectly normal and safe thing to do at the time, but the trouble is that however loving the relationship may be when you send it, however much you may trust the person you are sexting, can you ever know what the future will hold?

In my day of course, before we all had smartphones and still communicated via pigeons and slates, it wasn't an issue. You might have sent letters, possibly made the odd private video, but there were only ever one copy of these - easily found and destroyed, not so easily shared. Nowadays it takes just a second, one button - "upload" - and your most intimate moments and thoughts are out there for the world to see. Forever.

I'm not saying you have to close yourself off - suspect everyone and deny your sexuality - but please just be careful. Stop to think before you commit thoughts and images to cyberspace, because the minute they leave your phone they cease to be yours.

Love Mum xx

PS You're going to nail that interview when it comes around, I know you are.

By Suzanne Whitton

Dearest daughter,

If I was sitting opposite you right now, you would probably be rolling your eyes in despair, or perhaps embarrassment, but this way, I hope that you will give my words a chance.

I know that you see yourself as a grown-up teenager, able to make decisions for yourself but trust me, sometimes your "uncool" mum only has your best interests at heart. Please hear me out.

Childline's Zipit campaign Smartphone app Zipit was launched by Childline to help teenagers refuse requests for explicit images of themselves

The free app offers users a choice of picture responses to send instead

Zipit also offers advice on safe online chatting and on what young people should do if they feel threatened or if an image becomes public Teenagers' anti-sexting app launched Childline's Zipit app

As I watch you blossom from a child into a young lady, my biggest prayer is that you retain your innocence for as long as possible. This doesn't mean that I want to "baby" you, it just means that I am trying my hardest to keep your life age-appropriate. On occasion you will think my decision and advice is unfair, even ridiculous, but as your parent, my greatest role in life to be the gate-keeper to your heart.

Every day I see girls of your age - just 13 and still children - posting suggestive images of themselves, on Facebook and Instagram, photographs which once in the public domain, cannot be erased. I am shocked and saddened by these girls' eagerness to flaunt their adolescent bodies, pouting in front of the camera lens, taunting young boys and even grown men. With the arrival of Snapchat - an app which promises to leave no trace of your image online - the temptation is likely to be greater. My instinct to protect your innocence however, emerges even stronger.

Please stop and think before you post. Who is going to be seeing this image? Who might they send it on to? What impression of yourself are you leaving with that person? Please consider if it is the right one, the one that you want them to remember you by.

Can I ask one more thing? That you respect yourself - not only the teenage-self that you are now, but the adult that you will one day become.

Your ever-loving Mum x

By Erica Buteau

To my 12-year-old daughter,

We've talked about saying no. You know that you should always say no to drugs, no to sex or inappropriate touching. You understand stranger danger. But, what about what happens when you are alone at home? I want to be sure that you understand how dangerous the internet, and even your cellphone can really be.

I know we've talked about "stranger danger" and false identities before. But, what about that friend or boyfriend? You know, the cute boy at school that you gave your number to. Or, the one that you sometimes instant message with. I know how much you like him and how much you want him to like you back. What scares me is that I don't know if you have the self-esteem and the confidence to draw the line.

The sad truth is, boys will sometimes ask you to send them pictures of you or talk with them about sex over text or instant message. This is called "sexting" and it's not okay. Even if you trust this boy completely, once you hit send you can't take it back. The picture of you revealing something private can easily be forwarded to friends, posted on the internet and most likely will get into the wrong hands. (And, remember, you can't ever even be sure who is on the other side of the computer, cellphone or chat or that the person you are talking to is alone.)

Think about how you would feel if you sent a picture or dirty text to someone. Are you respecting your body? Are you respecting your privacy? What guarantee do you have that the recipient of that message will do the same? Can you trust that person with your reputation or even your future? Remember, there are no take backs. Once it is sent, it's as good as on the internet or being passed around school. Remember, one chance, one life. There are no take-backs.

Love,

Mom

By Emma Bradley

Dear daughter,

Being a teen is much harder today, you are subject to social media which invades your very being. You live your life by sharing, from the selfies you Instagram to the thoughts you tweet. Thankfully I never had that to manage alongside the usual teenage relationships I would write letters to my friends and boyfriends but they didn't have the ability to share so widely, no chance of a private conversation going viral.

I want you to be wise online and stay safe. One of the concerns I have is with photos and sexting. Not only am I your mum, but I'm teacher who has heard some horror stories. Girls that have sent compromising photos of themselves that have then been shared around the school like a holiday snap. I don't want you to feel the hurt and humiliation that goes with that particular mistake.

Getting too drunk, having your heart broken - those will be your experiences to feel. But just listen to your mum and don't ever give anybody photos of you that you wouldn't want everyone seeing and don't discuss your private life where it can be shared without your permission. School boys are not mature enough to deal with that - no matter what they say.

Once a photo is out there, you have lost control of it. It will be out there forever in someone's phone, memory stick or the internet. It could come out again when you least expect it. You have high aspirations, you want to be successful and you are working so hard at school to achieve your dreams I don't want that to be jeopardised, do you want a photo resurfacing when you are at the top of your chosen career or when you are a mum yourself?

Like I said sweetheart, make mistakes, your dad and me will cover your back, we will always be there for you but on this occasion just listen to us.

Additional reporting by Olivia Sorrel-Dejerine

Follow @BBCNewsMagazine on Twitter and on Facebook