This paper is my thesis as part of my studies at the Department of Informatics, at University of Piraeus for the Postgraduate Programme in “Techno-economic Management & Security of Digital Systems”. Scope of this paper is to introduce to the reader with the basics of PCI DSS and to guide and provide any sort of assistance to organizations willing to achieve compliance with the Payment Card Industry Data Security Standard (PCI DSS). As for its practical section, a PCI DSS readiness project has been delivered to a certain Organization willing to determine its level of compliance and get prepared for the PCI DSS assessment.