This book is a part of the courseware on Diploma in Banking Technology; (DBT) being offered by the Indian Institute of Banking & Finance. The book has been revised as per the new syllabus and covers topics like IT Security Standards, Web Security, Security in different banking channels, Disaster Recovery and Business Continuity, Overview of Computer Viruses, Cyber Crimes etc. The book has four modules namely: a. Introduction to IT Security b. Application Security c. Computer Threats & Viruses d. IT Security Policy and Systems Audit The book written for the Bankers, would also be of interest to the general reader, who is keen to learn about the security aspects involved in electronic banking.