Abstract: This paper discusses several important algorithms used for the encryption and decryption of data in all fields, to make a comparative study for most important algorithms in terms of speed (implementation) and security (special keys) determine whether an encryption algorithm is good. What is more, computational resources, such memory (RAM) size, are an integral consideration since they affect algorithm efficiency, hence the need to ensure optimal resource allocation, etc. Particularly, encryption is the process of transforming plain text into ciphered-text, which cannot be understood or altered easily by undesirable people.