AAAA is a domain record, that is basically the IPv6 address of the web server in which the domain name is hosted. The IPv6 system was introduced to replace the present IPv4 system in which every IP address is made up of 4 sets of decimal numbers ranging from 1 to 255 e.g. 5.168.208.143. In comparison, an IPv6 address features 8 groups of 4 hexadecimal digits - from 0 to 9 and from A to F. The main reason for this change is the considerably smaller range of unique IPs that the current system supports as well as the rapid increase of devices that are connected to the Internet. A good example of an IPv6 address is 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you'd like to point a domain name to a web server that uses this kind of an address, you need to set up an AAAA record for it, and not the widespread A record, that is an IPv4 address. The two records deliver the same exact function, yet different notations are used, in order to differentiate the two types of addresses.