This document provides an overview and definitions of key concepts related to information and communication technologies (ICTs) and their application in tourism, known as e-tourism. It discusses how ICTs have transformed the tourism industry, moving from early computer reservation systems to today's global distribution systems and use of the internet. The document defines important terms like the world wide web, intranets, extranets, and defines the roles of intermediaries and infomediaries in the digital tourism landscape. It provides context on how ICTs have impacted business processes, distribution channels, and strategic relationships across the tourism industry.