Digital Encryption Standard
DES, was the standard for encryption for many years. An IBM design it had been standardized by NIST. Cryptographicaly a very sound design (no better attack is known that brute force) it is now deprecated because it's key size (56-bit) and block size (64-bit) make brute force doable for a reasonable budget. Also, DES, while often implemented very fast in hardware is painfully slow on common CPU, something that is not true of DES.
Although many security experts believed that the algorithm was weak because of NSA implication in the latter stage of its design still resist all knwon attack and it has been shown that NSA made it immune to the differential cryptanalysis attack that wasn't known by the civilian sector at the time. Wether it was by luck or knowledge is not known.
When DES is still used it is usually in the form of TripleDES, or 3DES, that is not considered compromised and many times stronger than DES. AES, however, is considered much stronger and is usually much faster.