The table lists common terms used with Certificate Authority (CA) authentication:

Chain of TrustA certificate hierarchy that enables you to verify the validity of a certificate issuer
CRLCertificate Revocation List (CRL).  A list of digital certificates that have been revoked by the issuing CA before their scheduled expiration date and should no longer be trusted.
CSRCertificate Signing Request (CSR). The request you submit to a CA to procure a certificate.
Intermediary CertificateA subordinate certificate issued by the root CA to issue end-entity server certificates. This results in a certificate chain that begins with the trusted root CA through to the SSL certificate issued to the end user.
OCSPOnline Certificate Status Protocol. A network protocol, described in RFC 2560  , that is used to determine certificate status.
.PEMThe .PEM extension is used for different types of X.509v3 files which contain ASCII (Base64 encoded) data.
Root CertificateA public key certificate that identifies a root CA such as Comodo DigiCert , or GlobalSign .