A Certificate Authority (CA) or Certification Authority is an entity that issues digital certificates. Anyone can issue SSL certificates, but those certificates would not be trusted automatically by web browsers. Certificates such as these are called self-signed. The Certificate Authority (CA) has the responsibility to validate the entity behind an SSL certificate request and, upon successful validation, the ability to issue publicly trusted SSL certificates that will be accepted by web browsers. Essentially, the browser vendors rely on CAs to validate the entity behind a web site.