The Data Encryption Standard (DES) is a symmetric-key block cipher used for the encryption of digital data. It was adopted as a Federal Information Processing Standard in 1977 by the National Institute of Standards and Technology (NIST). DES encrypts data in 64-bit blocks using a 56-bit key, employing a series of permutations and substitutions through 16 rounds of processing to transform the plaintext into ciphertext.

Although DES was widely used for many years, it became vulnerable to brute-force attacks as computational power increased, leading to the adoption of more secure encryption standards, such as the Advanced Encryption Standard (AES). In 2005, DES was officially withdrawn as a standard due to its weakened security compared to modern cryptographic techniques.

A cipher is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. In cryptography, a cipher transforms plaintext (readable data) into ciphertext (encoded data) to secure the information, making it unreadable without the proper key or method to decode it. There are various types of ciphers, including symmetric (where the same key is used for both encryption and decryption) and asymmetric (which uses a pair of keys).