The people who practice this art are known as cryptographers. As the Internet and other forms of electronic communication become more and more prevalent, electronic security is growing as well and becoming increasingly important. Cryptography is used to protect e-mails, corporate data or credit card information. One of the most popular cryptography systems on the planet, used by more and more users each day is Pretty Good Privacy. The reason this system is so popular is because it's effective and free. Cryptography systems can be broadly classified into symmetric-key systems that use a single key that both the sender and recipient have, and key systems that use two keys, a public key known to everyone and a private key that only the recipient of messages uses.
Cryptography concerns itself with four objectives. Confidentiality which refers to the information that cannot be understood by anyone for whom it was unintended. Integrity, referring to the fact that the information cannot be changed in any way during storage or transit between a sender and a receiver without the alteration being detected. Another key point is non-repudiation, which means that the creator/sender of the information cannot deny at a later stage his part in the creation or transmission of the information
A common encryption technique known as a simple substitution, substitution cipher, or Caesar cipher (named after roman emperor). This shifts the letters of the alphabet over a few characters. For example, the alphabet can be shifted over four characters. Though the terms cryptography and encryption are related, cryptography differs from encryption. Cryptography, in conclusion, refers to the science of secret codes whereas encryption is an actual cryptographic process. Encryption essentially means scrambling data using an algorithm so that only somebody with a secret key can access it.