LOC records allow WGS84 location to be published via the Domain Name Service. They are defined in RFC 1876.
If a host has a LOC record, it can be looked up via dig -t loc:
$ dig +short -t loc geoffstratton.com 32 47 32.599 N 96 48 53.11 W 125m 10m 100m 10m
LOC records are expressed in terms of Degrees-Minutes-Seconds, not decimal latitude and longitude. You can convert them using a tool like the FCC’s latitude and longitude converter.
Publishing a LOC record is pretty simple: just go into your DNS service and add a LOC record type for your domain name alongside your usual A, CNAME, and MX records. You’d probably be using BIND on Linux or Windows DNS.