Cryptanalysis is the art of breaking cryptosystems - seeing through the disguise even when you're not supposed to be able. Cryptology is the study of both cryptography and cryptanalysis. The original message is called a plaintext. The disguised message is called a ciphertext. Encryption means any procedure to convert plaintext into ciphertext.
Decryption means any procedure to convert ciphertext to plaintext.
A cryptosystem is usually a whole collection of algorithms. The people who are supposed to be able to see through the disguise are called recipients. Other people are enemies, opponents, interlopers, eavesdroppers, or third parties. DES Data Encryption Standard is an encryption block cipher defined and endorsed by the U.S. Government in 1977 as an official standard. Originally developed in IBM, it is the most well-known and widely used cryptosystem.