It's been ten years since Apple launched the iPhone. Smartphones have revolutionised the way we live - and have helped billions of people around the world stay in touch and become more productive.
But there's a downside to the smartphone world. Many of us are addicted to the gadgets, unable to put them down even while walking or driving.
Our US Correspondent Harry Horton has been looking at how smartphones have changed our lives - and at the dangers of becoming too addicted to our mobile devices.
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From dusk until dawn - many of us are never far from checking our smartphones.
Alarm clock apps wake us up in the morning. Phones monitor our fitness. Their maps help us get from A to Z. And they've made it easier to communicate with each other than ever before.
Collectively, Americans check their phones more than nine billion times per day. (1)
On the streets of Washington, most people told us they thought smartphones had a positive impact on their lives.
<<SOT: VOXES // English>>
"It makes life a lot easier for us it gives us a lot of information it makes all that information extremely accessible."
"It's a tool for us to communicate, to do different things, to book hotels to book your ticket."
"It's interesting how there's a literal significance to someone flipping their phone down when they're having lunch with someone or they're grabbing coffee or they're doing dinner"
But doctors warn that our love of smartphones might be dangerous. Checking your phone in bed can cause sleep and eyesight problems. (2)
Smartphones have even been blamed for an increase in pedestrian deaths - because of walking while texting, and because of distracted drivers. (3)
But perhaps the most consequential impact comes from addition. Recent studies suggest more than a quarter of adults and half of US teenagers feel addicted to their mobile devices.
At the Washington Latin Public Charter School, principal DIANA SMITH thinks smartphone use amongst children has become severe.
<< SOT: PRINCIPAL DIANA SMITH, Washington Latin Public Charter School // English>>
"I must have had four or five stories from families who said their kids were up texting until two, three, four am in the morning. And so I asked a lot of kids about that and I would say over ninety percent of the kids said they were up until two and four am and that they're sleeping with phones under their pillows."
To help break the habit, this summer the principal set a radical challenge: If children could spend each Tuesday of the summer break off electronic and video screens, they would get a one hundred dollar cash reward.
Fourteen year-old Ava Pugh was one of thirty eight children to successfully complete the challenge. She said she felt more than just a financial benefit.
<< SOT: AVA PUGH, Eighth grade student // English>>
"I think it was a really good experience because I ended up sleeping better, since I feel like the screens had an effect on my brain and how long it wanted to stay awake and I was sleeping better I did a lot more reading and I feel like I lived a better lifestyle."
Smartphones have revolutionised the way we live our daily lives and have brought undoubted benefits - but the technology is so recent it could decades before we truly know what dangers and mobile phones might pose.
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