More than half of UK adults are risking their online security by using the same password for most if not all websites they visit, according to research by regulator Ofcom.
Ofcom's study found 55% of adult internet users use the same password, while 26% say they tend to use easy to remember passwords such as birthdays or names, potentially opening themselves to account hacking.
A quarter (26%) said they have problems remembering passwords.
However, the Adults' Media Use and Attitudes Report also found that adult internet users are increasingly adopting security methods online, with 62% protecting their wi-fi internet connection, up from 52% in 2011, and 61% considering measures such as checking for padlock symbols or secure system messages before entering personal details, up from 56% in 2011.
Among smartphone owners, 75% use a screen lock and 50% have pin protection for their sim card.
The average adult internet user estimates they now spend almost 17 hours online every week, up from 15.1 in 2011.
Meanwhile, reported incidents of spam, viruses and phishing emails by internet users have all remained stable compared with 2011.
The average user claims to visit 19 different websites in a typical week, with men visiting 24 sites while women visit 14.
However, despite the increasing length of time spent online, more than a fifth (22%) say they visit fewer than five websites in a typical week.
Ofcom's director of research, James Thickett, said: "While our research shows that some people are still taking security risks online, they clearly feel these are outweighed by the benefits that the internet brings.
"We are seeing more and more adults turning to the internet for information and as a way of keeping in touch."
The study also found that older internet users are increasingly turning to social networking to keep in touch with friends and family.
More than a third of 55 to 64-year-old internet users (35%) have a social networking profile - up by half in just one year.
A quarter (25%) of internet users aged 65 and over also say they have a profile, meaning that about two thirds (64%) of all adult internet users have a social networking presence, up from 59% in 2011.
The research revealed that the average UK adult with a social networking account has 237 friends on their main profile, such as Facebook.
Younger adults have more online connections, with the average 16 to 24-year-old social networker claiming 352 friends, almost three times as many as those aged over 45 at 126 friends.
Half of adults (50%) with a profile visit more than once a day, up from a third (35%) in 2011.
Almost one in 10 (9%) adults is an "avid" user, checking their profile more than 10 times a day.
Those aged 16 to 24 are the most likely to do so, with almost a fifth (17%) checking for updates more than 10 times daily.