HOW TO find the city and ISP of a visitor to your website.

Fetch the visitor's IP address using Request.ServerVariables("REMOTE_ADDR") [in ASP & ASP.NET] and use one of the many IP address lookup databases available on the web, some of them for free. The price of these databases may vary depending on the accuracy, frequency of database updates, features it offers like Region/State, City, Latitude, Longitude, ZIP Code, Domain Name, Time Zone, Connection Speed, Proxy (including anonymous and open proxies) detection and may run into hundreds of dollars.