An Ofcom study also finds that most people make use of around only half of the apps they download to their devices.
The number of older people going online has soared, driven by the uptake of tablet devices and smartphones, according to Ofcom.
Among those over 65, internet use rose by 25% in just a year, mainly because of the popularity of tablet devices among that age group.
The Ofcom report provides a comprehensive overview of the UK population’s media use.
It says young people are spending more than 24 hours a week online.
But 16-24 year olds are also better informed about privacy and security than typical UK adults, who spend an average of nearly 17 hours online per week.
Although laptop and desktop computers remain the most popular way of accessing the internet, two-thirds of adults now use other devices like smartphones and tablets.
Twice as many people now use tablets as they did in 2012.
Smartphones are also getting greyer. Six in 10 adults now use one, mainly driven by increased ownership among 45-54 year olds.
As a result, gamers are getting older: Playing games on a smartphone has more than doubled among 45 to 54-year-olds and 55 to 64-year-olds.
On tablets, the number of gamers in those age groups has tripled since last year. Those older than 45 now spend more than four hours per week playing games.
But on smartphones, more than half the apps installed are never used.
Ofcom found that most people only use 10 apps regularly, out of an average of 23 installed.
Facebook was the most popular social network, followed by Twitter, YouTube and WhatsApp.
The average person has 228 friends online – a number that is unchanged since 2012.
Women are slightly more likely to have a Facebook profile than men, but men are significantly more likely to use Twitter, YouTube and MySpace.
