With either type of traffic tracking, the names and e-mail addresses of the visitors themselves usually remain anonymous unless they voluntarily provide it. If visitors provide that, they might also be willing to provide demographic information about themselves, such as where they live, their income level, and a few details about their family's purchasing decisions. Gathering this data at Web sites is becoming more common as the Web grows. Companies need this information because it helps them focus the site to visitors' demographic profiles. E-mail addresses are important because mailing lists are valuable as a way to attract repeat visitors and recruit new ones by word of mouth.
Some companies require visitors to register before they can even access the site.
On that page, a notice explains that in order for advertisers to continue to sponsor the site, or in order for the company to customize the site to visitors upon their return, registration is necessary before the visitor can delve further. At that point, visitors can either leave or continue with the registration process. The registration form is typically only a page or two and usually doesn't ask for full names and mailing addresses. Most Web users don't want to provide that much personal information. Instead, surveys ask for general information like age, interests, income, and family statistics.