What it is
TXT records let a domain publish arbitrary text in DNS. In practice they are used for proving ownership of the domain to third parties, and for email authentication policies such as SPF and DMARC.
Why it matters
TXT records are a running inventory of the services an organisation uses. Verification strings from Google Workspace, Microsoft 365, Atlassian, Zoom and dozens of others each carry a recognisable prefix, so the record set often names the internal toolchain outright.