A certificate authority (CA), also sometimes referred to as a certification authority, is a company or organization that acts to validate the identities of entities (such as websites, email addresses, companies, or individual persons) and bind them to cryptographic keys through the issuance of electronic documents known as digital certificates. A digital certificate provides: Authentication, by serving as a credential to validate the identity of the entity that it is issued to. Encryption, for secure communication over insecure networks such as the Internet. Integrity of documents signed with the certificate so that they cannot be altered by a third party in transit.