They pass around your private information and manipulate your attention so they can sell it. Yet still we spend hours a day on the world's biggest social media platforms - but should we? This Herald series explains exactly what's at stake when you like your friend's Facebook post, Google symptoms when you're sick and share fake news.
After a day of skiing in one of Canada's most beautiful resorts, Dr Samantha Marsh and her friend went out for dinner.
But her friend couldn't hold a conversation - the lure of her phone was too strong.
"She was checking her phone constantly and I thought, 'We're in Whistler. We're at dinner and this should be such a nice experience but you're stressed out and anxious.'
"She was constantly distracted and not present at all. She couldn't even hold a conversation with me."
The friend was waiting for a message from a new romantic flame and in its absence was obsessively checking social media.
Marsh is a research fellow at the University of Auckland and helps families find a digital balance. She has seen the ugly effects of our addiction to screen time.
She's been told of teens threatening to kill themselves at the threat of their phone being taken away and young children throwing their parents' smartphones in the bin.
But the experts say we're not doomed forever - we just need to learn how to regain control.
"I always like to say, 'Make sure you're using your device and not the other way around,'" says mental health promotion specialist Ciaran Fox.
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Social media has become so enslaving that some of the people who had a hand in its creation have gone public with their regrets about what it's become.
Early Facebook investor Sean Parker said in 2017 that the company deliberately made Facebook as addictive as possible by exploiting human vulnerabilities through a validation feedback loop.
"God only knows what it is doing to our children's brains."
Parker says Facebook wants to capture as much time and conscious attention of its users as it can.
"And that means we need to give you a little dopamine hit every once in a while because someone liked or commented on a photo or a post or whatever.
"And that's going to get you to contribute more content, and that's going to get you more likes and comments."
Digital ethicist James Williams says different technologies, which were once designed to enable connections and save time, now battle for our attention.
This can end up distracting us from "living the lives we want to live", he says.
In New Zealand, we spend an average of five hours and 55 minutes on the internet, including one hour and 43 minutes on social media, according to a 2018 GlobalWebIndex survey.
And 81 per cent of the population has a smartphone.
Local research about how social media and heavy smartphone use affects adults is scarce but numerous international studies point to it having a negative impact on our wellbeing.
One paper by Britain's Lancaster University finds users risk becoming more addicted to social media even as they experience stress from its use because, instead of quitting, they just use the same platforms differently.
Though a new study from a Kiwi researcher that has dug into how platforms like Facebook, Twitter and Instagram influence our psychological wellbeing suggests it's not as bad as a lot of people think.
In fact, the weak link the Kiwi researchers have found is comparable to playing computer games, watching TV or minding kids.
Christine Macfarlane, New Zealand Association of Counsellors president, says our addiction to social media and smartphones has very real negative impacts on lives.
"Screen time has taken over."
Macfarlane, who specialises in mindfulness, says the trend to message someone rather than call means often a lot gets lost in the tone and can cause tension.
And communicating through social media makes it a lot easier to pick fights and say things someone would likely never say to another's face.
"People are so much nastier online."
Romantic relationships also suffer through this disconnect because people are more willing to send nude pictures of themselves or "sext" when they're not intimate in real life, which can add pressure, says Macfarlane.
And the constant ability to access porn on your smartphone has affected expectations of sex, she says.
Social media can also enhance any mental health issues.
"It makes it worse because it increases people's isolation, particularly in adolescents who've always had the internet and so that's just the way they communicate.
"So the isolation that it causes for teenagers and young people is worse because they haven't got that foundation of communication like adults do."
Young people are also more vulnerable to the trappings of social media because they haven't got the brain development and cognitive maturity that older adults have, Macfarlane says.
Mental health promotion specialist Ciaran Fox says smartphones, and how we use them, are damaging to any brain because they encourage multitasking - which isn't a good thing.
"Multitasking is when you have many, many things splitting your attention all the time, which then conditions your mind to get habituated to the idea of divided attention so it's hard to focus on one thing at a time.
"It means we're less present because we're always connecting to things which are happening elsewhere and are focusing on the feedback we're getting from our devices rather than the feedback our bodies are getting from the moment."
The breakdown of the family unit
Smartphones, social media and our addiction to them both imposes on family time and affects children's learning as parents prioritise their screens, says Marsh.
She says when parents pick up their phones, they often miss opportunities to interact with their children and teach them about their environment.
Around "annoying times", like when you're making dinner, it's tempting to plunk your child in front of a screen but by doing that you're missing out on an opportunity to teach them something.
And some children are starved for attention because of it.
"It's not unusual for me to be told of kids who throw their parents' phones in the rubbish bin and stuff like that.
"And that's a pretty clear message coming from your kids."
Marsh says she understands because she has two young children, and gives the example of when she got a work text while looking after her daughter.
"She asked me a question and I snapped at her, and the only reason I did that was because something invaded my home life which shouldn't have. It wasn't appropriate.
"And every once in a while is fine, but it's when that becomes the norm because you're engaged with your screen and it impacts on those relationships."
Health experts are warning mums of a modern-day habit of being on their phones while breastfeeding. Dubbed "brexting", they fear it may damage crucial bonding with their newborns.
Dr Harry Nespolon, Royal Australian College of General Practitioners president, says a baby seeing and responding to Mum's face is disrupted if they're on their phone.
He says taking care of very young children means you could be socially isolated because it might be very difficult to get out.
"But breastfeeding time is not the time to catch up with Facebook".
Marsh says the conversation with your children about screens changes as they grow older.
Parents can control children's screen use when they're young but when they're teens you need to have a different conversation.
During adolescence, young people's brains develop and they need to learn how to build and maintain relationships.
Constant notifications from social media and a smartphone addiction can impair this, Marsh says.
As well, they need to know about the dangers of online harm.
"Other commentators say you should only get a phone for your kids when you're ready for them to see porn.
"Because, basically, as soon as they get a smartphone, they're 100 per cent going to see porn, so is your kid okay to handle that?"
We can fix it
But there is hope - we can come back from the brink of social media and smartphone addictions, says Fox.
He helped the Mental Health Foundation and the Canterbury District Health Board launch the All Right? campaign, which encourages people to do a "digital detox" and get away from their devices.
Smartphones and social media aren't inherently evil, despite their being designed to be addictive, and there is little point in demonising them because "we've already opened Pandora's box", says Fox.
"The devices themselves aren't bad.
"But if what you're doing with it all day is comparing your life to the perfectly curated lives of others on Instagram and you're feeling bad about yourself, then that's not going to be good for you.
"It's about whether your use is 'significant' or 'problematic' and there is a difference."
He says research is emerging about there being a clear distinction between using your phone or social media heavily without it affecting your life and mental health and someone using it to the point that it is damaging.
And we need to ask ourselves where our balance is, Fox says.
"I always like to say, 'Make sure you're using your device and not the other way around.'"
He encourages people to check their own feelings after they use social media to determine whether they have a problematic relationship with it.
If you feel good after using it, your usage is probably fine. But if you scroll Facebook for an hour and it makes you feel bad, it's likely your social media use is damaging.
"And if you're letting it interrupt conversations or family mealtimes in favour of communicating with people who are thousands of miles away, that's not a good connection - you're missing out on the connections in front of you.
"If your friends and family are saying, 'You're always on your phone and it would be good to see you for a little bit,' maybe that's worth listening to."
And if it is problematic, Fox encourages those people to make their phones less addictive through a few quick changes - take breaks away from technology and try to find something you enjoy doing away from a screen.
"We can definitely fix it - it's like any addiction. You can come back from it."
Make your phone less addictive
1. Check your screen time
APPLE: Settings > Notifications, Sounds, and Do Not Disturb > Screen Time to see your usage statistics. You can also check your child's screen time if it's connected to your device.
ANDROID: Settings > Battery > Screen use since last full charge. You can also download the Digital Wellbeing app for further insight and control.
2. Turn on an automatic Do Not Disturb function so you're not woken
APPLE: Settings > Do Not Disturb > Set a schedule when your phone will automatically switch to Do Not Disturb
ANDROID: Settings > Sound > Do Not Disturb > set schedule and what apps, notifications to block. You can also set different schedules.
3. Turn off bluelight and set a bedtime
APPLE: Settings > Display & Brightness > Turn on Night Shift and set preferences, including schedule and how warm to make your phone's light.
You can also set a bedtime in the Clock app > Bedtime > Set schedule to remind you to stop using your phone and wind down.
ANDROID: Settings > Display > Night Light > set schedule
4. Use greyscale to make your phone less appealing
APPLE: Settings > General > Accessibility > Accessibility Shortcut > Colour Filters. Now, you just press the home button three times to enable greyscale. Triple-click again to go back to colour.
ANDROID: Swipe the notification shade down from the top of your device and tap "edit" in the bottom left > Add Greyscale to your tiles to enable easy access.
You can also schedule it through the Digital Wellbeing app.
5. Turn off notifications for distracting apps
APPLE: You can do this manually in the notification centre for apps you know to be distracting or you can download an app to block your social media apps.
ANDROID: Within the Digital Wellbeing app you can set a Focus schedule, which will block notifications for chosen apps for set periods, for example during work hours or dinner.