Five years ago retailers were still debating whether or not there would ever be a large enough online customer base to make Internet advertising and website development economically feasible. No more. In another five years it will be nearly impossible to find someone over 18 who hasn't shopped online.

Burst! found that three out of five (62.8%) online shoppers say the Internet is their primary source of information when evaluating and comparing products — far outdistancing the number two source, print media.

Of particular note to retailers, big spenders are shopping online. Burst! found that as a respondent's reported household income increased, so did the likelihood that the Internet is the primary comparison-shopping tool. In fact, the percentage of respondents who said the Internet was their primary tool for comparison-shopping increased from 59.0% for those reporting household income of less than $35,000, to 70.6% for households reporting income of $75,000 or more.

For this holiday season, four out of five (83.2%) shoppers said they expect to use the Internet to research or purchase gifts — and two out of five (44.3%) said they will use the Internet more than last year.

"As our data shows, the Internet reaches a great many people who are poised to make buying decisions," said Jarvis Coffin, CEO of BURST! "The trick for advertisers is to determine how and where to reach them before those decisions get made."

It must be remembered that online "shopping" does not necessarily mean "purchasing." The BURST! study reveals that among those who shop online, slightly under half of them actually make purchases online, while slightly over half only window-shop.

Even so, whether the items are eventually bought online or not, Internet shopping is indisputably a powerful influence on the purchase decisions of growing numbers of shoppers.

For more information about current online shopping trends, read eMarketer's Online Holiday Shopping Preview.