This book is an attempt to exploit the full potential of existing tools, techniques, and methodologies to provide situation awareness and advisory support to end-users in a seamless manner. The nature of information input to a Decision Support System (DSS) is majorly unstructured or semi-structured, making the decision-making process complex. The heterogeneity of information sources is easily dealt with by incorporating semantic technologies and hence facilitating intelligent situation awareness and decision support. This book presents to the reader the prototypical development of a knowledge-driven situation awareness and advisory support (KDSAAS) in the emergency domain. KDSAAS applies semantic technologies to provide real-time information in order to provide intelligent decision support. This introductory chapter advocates the importance and utilization of semantic data models in achieving semantic intelligence, which is a prerequisite for successful decision support systems. A few use cases demonstrating the importance of semantic technologies for decision support systems are also presented.