Where is IP whois lookup used?
IP lookup tools are used to determine the origins of online visitors. Whenever someone visits a website, the IP address of the visitor is sent to the web server. An IP address lookup allows the webmaster to track through which network the visitor is connected and in some case also to identify the location (region) of the online visitor.
If the online visitor is using a shared internet connection, for instance through an internet access provider, it becomes harder to determine the precise location, because there are many online visitors using the same IP address in the network of the access provider.