When importing a key and certificate for SSL, three crucial files are required: the Private Certificate, the CA certificate, and the Private Key. The Private Certificate is the certificate for the server, proving its identity. The CA certificate is needed to establish trust, as it contains the public key of the Certificate Authority that issued the server certificate. The Private Key is used to establish secure communication. The Public Certificate is not required for importing; it is typically downloaded to validate a certificate's authenticity but not for the import process itself.