They predict advertising, not subscriptions, will be the main source of revenue for companies offering information and entertainment on the Web. The numbers are amazing, but, I think, very realistic. On my opinion, advertisers on the Internet are almost all the companies that can see the necessity in advertising and promoting their products. Many of them do not know how to do it, and results are not predictable in many cases, but potential customers are there. They are surfing the Cyberspace for new products, so market is open, and every business tries to get more out of that new phenomenon - the Internet.
Audience are the people who have access to the Internet.
There is basically no limit in the age, race, education, or income. Computers and access to the Internet itself are pretty affordable. A lot of companies are working on creation of cheap devices for the Internet use, and the slow speed problem will be solved soon. The Internet will attract more and more people, and it means advertising in the Cyberspace will play one of outweighing roles in marketing. Companies owned Web sites and using different popular Web sites for promotion of products and services.