Young women are now the most dominant group online in the UK, according to new research from net measurement firm Nielsen/NetRatings.
Women in the 18 - 34 age group account for 18% of all online Britons.
They also spend the most time online - accounting for 27% more of the total UK computer time than their male counterparts.
Of UK males active online, the 50+ age group is the most prevalent.
The breakthrough of these groups will come as a surprise to many who regard the Internet as being largely dominated by young men.
Variety of sites
"This represents a seismic shift from the early days when the internet was the domain of the techno-geek," said Alex Burmaster, an analyst with Nielsen/NetRatings.
"If you asked the question 'who spends the most time on the computer' - most people would still answer 'men'," he added.
The fact that new groups are emerging is the best illustration of how mainstream the net has now become, he said.
Women in the 18- 34 category are visiting a variety of sites including those dedicated to fashion, family and lifestyle issues.
While sites dedicated to childrearing dominate the top ten, for younger women it is the websites of high street stores such as Miss Selfridge and H&M that are the most popular, along with social networking sites such as Facebook.
A recent report by Forrester Research found that, in the US, spending on clothes and accessories had outstripped the sale of computer equipment for the first time in 2006.
In 2007 Forrester estimates some $22.1bn will be spent on clothes, accounting for 10% of all clothing sales.
Even in the traditionally male-dominated world of gaming, women are catching up, according to figures from the Entertainment Software Association.
They now account for 38% of game players. Women over 18 represent a significantly greater portion of game players compared to boys under 17.