18- to 44-year-olds comprise half the Web population.
Since 2005, the population segment that has made the largest online gains in the United States is the 70- to 75-year-old age group.
While just over one-fourth (26 per cent) of 70-75 year olds were online in 2005, 45 per cent of that age group is currently online.
Youths dominate the Internet population; the study showed: 93 per cent of 12- to 17-year-olds were online in 2008, compared with 89 per cent of those 18-24, 83 per cent of those 40-44, and 62 per cent of those 60-64.
Email use among teens slipped from 89 per cent in 2004 to just 73 per cent last year.
Some 78 per cent of 12- to 17-year-olds play video games online (more than twice the rate for adults overall), 68 per cent send instant messages, 59 per cent download music and 49 per cent read blogs.
Of older Baby Boomers (55-63 years old), only 21 per cent download music and 25 per cent read from blogs.
And 10 per cent of those 12-17 visit virtual worlds, compared with just two per cent of adults, the survey showed.
Of Generation Xers (33-44 years old), fully 82 per cent seek out health information online, about the same rate as those 73 and older.
Generation X is also most likely to shop online (with 80 per cent doing so compared with 71 per cent for the 18- to 32-year-old Generation Y), manage their bank accounts online (65 per cent) and consume news on the Web (76 per cent).