An IP address, short for an Internet Protocol Address, is a series of either four or six 3-digit decimal numbers which are presented in a long line separated by periods (full-stops). This string of numbers and dots is unique to each computer.
The purpose of an IP address is to locate the computer on the internet. It can be used to effectively rout traffic to and from the device or server, or to forensically locate a web user from the code of their IP address. IP addresses can be hidden in various ways, including with the use of a VPN.