Certificate Transparency - Definition from the Hotspot Shield Glossary
Certificate Transparency is concerned with making the creation, issuing and ownership of digital certificates as transparent as possible to stop forged signatures being created and used illicitly.
A major problem with the use of digital certificates is if they are forged - If a hacker uses a forged certificate that looks authentic, why would they be denied access to a network or stopped from receiving information? Furthermore, people creating forged certificates could use them to pose as a business to steal personal information from unsuspecting users. To combat this, Certificate Transparency was introduced with three specific goals: The protect users from being harmed by the use of certificates, to provide an auditing system where certificates can be checked for authenticity, and to make it difficult for CA’s to provide certificates to a domain without that certificate being visible to the domain owner.