Cryptography is a process of communications. Even when encrypting information for storage, it is still a process of communications. You may be communicating with someone else or with yourself at some future time. Encryption implies decryption.

Cryptography takes something readable (by man or machine or whatever) or usable and makes it unreadable, except under specific circumstances.

Cryptography is reversable. If you encrypt something, it needs be decryptable. The intended recepient must be able to decrypt what you have encrypted.

Information is not destroyed by cryptography. It is merely made unavailable until the circumstances are satisfied that make it possible to decrypt in and make it available again.

Even ROT13 is a form (abet a limited one) of cryptography. ROT13 takes something readable and makes it unreadable by anyone whom I don't intend to read it. In this case, the people I don't want reading it are the ones who would object to it's content if they read it accidentally. In this case, secrecy is not the goal but, rather, insuring intent. If someone reads the contents of the message, then they intended to read it and that is whom I wanted to read it. It met my goals of taking something readible and making it unreadable to those whom I didn't want reading it and yet readable to those whom I did.