The DNS-specific TXT record allows the storage of any textual information associated with a FQDN. Created very early in the RFC1464 in 1993 in order to associate information to hosts and devices on the network, it proposes a format for storing keys and values. Multiple TXT records can be associated to the same FQDN.
This TXT record is mainly used today for storing SPF and authorization keys from server providers. In certain circumstances, it can also be used by command and control servers to pilot malware by indicating what the next action is to perform.