Basic ideas about existing tools, algorithms and mathematical models of computer steganography are given. Described are models of hidden storage and transmission of information in information computer networks, architectures of software systems for steganographic conversion of information. Analysis of practical aspects of implementation of software systems of hidden information transfer and methods of steganographic transformation is given. For specialists in the field of information protection and graduate students studying in the specialties "Computer Security," "Integrated Security of Automated Systems."