The data package includes the public key that belongs to the entity. The version field identifies the certificate format. The Signature Algorithm identifies the algorithm used to sign the certificate.
Subject is the name of the user to whom the certificate is issued.
The subject's public key field includes the algorithm name and the public key itself. The last field is the CA's signature. In order for digital certificates to be effective, the users of the network must have a high level of trust in the certificate. But what happens if someone doesn't trust the CA - perhaps the person has never heard of the CA before. This problem is addressed in the certifying process by something called the hierarchy of trust.