The use of the Internet for various purpose including social, business, communication and other day to day activities has been in common place. The information exchanged through Internet plays vital role for their owners and the security of such information/data is of prime importance. Knowing the concepts, principles and mechanisms for providing security to the information/data is very important. So here are some basic security concepts like symmetric and asymmetric cryptography, hashing, message and user authentication, digital signatures, key distribution and their code.