The trend created a female majority in cyberspace for the first time.
Female Internet users outnumbered men and boys online in the United States in May, a reversal from the early days of the male-dominated Internet, according to a report released Wednesday by Internet market research firms Media Metrix and Jupiter Communications. Female users accounted for 50.4 percent of U.S. Internet users that month.
Women have been slower to go online than men. Female users made up only 38 percent of all Internet users in 1996 â€“ but their ranks have grown ever since. They reached parity with male users in February.
"This is definitely not a one-time outnumbering of men," said Media Metrix analyst Anne Rickert. "It's a trend that suggests women are favorably positioned for further growth in the years to come."
By far the biggest increase over the past year was for girls ages 12 to 17. Their ranks online soared 126 percent, while the number of boys that age who went online rose only 45 percent.
Researchers found teenage girls are flocking to chat rooms and Web sites for their favorite magazines, fashion styles and rock bands.
Women over 55 also signed online in droves. Their ranks increased by 109 percent during the year, with various genealogy, health and fun Web sites drawing large numbers of older women.