Security
CT
Abbreviation for Certificate Transparency
In short and in plain language
CT is a public log for certificates.
It records which ones have been issued for a domain.
Site owners can watch the entries. So they can spot ones for their domain that they did not expect.
This can help in keeping an eye on a website.
Definition
CT is a public logging system that documents the issuance of certificates for domains. Operators can watch the entries and so detect unexpectedly issued certificates for their domain. This can help in monitoring a website.