Any web security system should achieve three conceptual goals are; confidentiality, integrity and Non-repudiation, and authentication. Also any system of communication when it is designed with these security services are taken into account and these security services must be defined and can be shortened format as (CIA).In this paper, we are going to discuss the theoretical background on the objectives of web security, and it will be touched upon the other subjects such as symmetric cryptography, asymmetric cryptography, the hash function, confidentiality, integrity, non-repudiation, Authentication, Communication and Network Security and its types ,and we will focus on the digital signature concepts.