Each computer has a name, MAC address (hardware id) and an IP address which can identify you on the internet or a network. When you visit a webpage that web server can identify your public ip address. This is saved in the web server logs with a date and time and any resources (webpages) you may have accessed.
IP is short for “Internet Protocol” and identifies you with a numeric code. Just as you have a mailing address for your home, in order for the postal service to locate you.