Each device that's connected to the world wide web has a unique identifier known as IP (Internet Protocol) address. This includes personal computers, web servers, smart phones, switches, etc. The pool of IP addresses, that was introduced initially, has already been distributed, therefore the so-called IPv4 IP addresses are slowly getting replaced with IPv6 addresses. Every domain which opens a website has an IP record, which is the address of the server where it's hosted. When using the IPv4 system, the record is called A and it consists of 4 sets of numbers from 1 to 255 divided using a dot, while with the IPv6 system it is called AAAA and it is made up of 8 groups of hexadecimal numbers i.e. this sort of records use digits from 0 to 9 and letters from A to F. An example of an AAAA record is 2010:0c48:43d3:2142:1012:8c3a:2475:2435 and this format can handle a considerably bigger number of IPs than the IPv4 format.