Over the last decade the world has seen an astounding growth of information technology that has resulted in significant advances in cryptography to protect the integrity and confidentiality of data. The most affected is the financial sector and the e-commerce over the Internet, which requires secure data transfer, or handling during any transaction of business. Secrecy is the heart of cryptography. Encryption is a practical means to achieve information secrecy. In this aspect DES (Data Encryption Standard)- A symmetric key cryptography and its variant triple DES, has over the last three decades played major role in securing data in this sector of the economy and within other governmental and private sector security agencies. In this study the theory and implementation of DES and its suitability in securing data in future will be described. Comparison with other symmetric key crypto-algorithm will also be considered.