certificates - aka Certificate Signing Request (CSR) which becomes TLS Certificate when signed by a Certification Authority (CA)
certificate authorities - aka Certification Authority (CA)
certificate repositories - a list of TLS Certificates
certificate revocation mechanism - methods include: Certificate Revocation List (CRL), etc

Obtaining an SSL/TLS Digital Certificate (Enabling HTTPS)

from Certificate Signing Request (CSR) to SSL/TLS Digital Certificate

PKI Components

PKI Components	Description
Certification Authority (CA)	is a Trusted Intermediary that: holds a public-private key pair uses its own private-key to issue/sign a: Certificate Signing Request (CSR) which then becomes a TLS Certificate Certificate Revocation List (CRL) to verify whether a CSR or CRL was signed by a CA, we use the CA’s public-key. All trusted CA public-keys come pre-package in the operating system Link to original
Certificate Signing Request (CSR)	is a block of encoded text that is given to a Certificate Authority to be signed which then becomes a TLS Certificate. Link to original
TLS Certificate	is a Certificate Signing Request (CSR) that has been issued/signed by a Certificate Authority certifies the ownership of a public key by the named subject of the digital certificate Link to original
Certificate Revocation List (CRL)	is a list of digital certificates that have been revoked by the issuing Certificate Authority before their scheduled expiration date and should no longer be trusted a digital certificate is valid if: it has a valid CA signature not expired is not listed in CRL Link to original