This module explains the growing number of Application Servers and their variants (Mobile Application Servers, Commerce Servers, B2B Servers, Multimedia and Collaboration Servers). This is one module of an extensive handbook that systematically discusses how to translate e-business strategies to working solutions by using the latest distributed computing technologies. The focus of this module of the handbook is on application servers that package several middleware and infrastructure services into a platform for development, deployment, and management of modern applications. Chapters of this module explain the principles of application servers and systematically discuss a) Mobile Application Servers based on WAP, I-Mode, J2ME, and others; b) Commerce Servers based on e-payment systems, electronic catalogs, XML, secure C2B trade; c) B2B Servers based on ebXML, Web Services, workflows, EDI, EAI; d) Multimedia and Collaboration Servers based on groupware, SMIL and RTP; and e) ©Super Application Servers© that combine numerous services needed for Web, mobile applications, and EC/EB applications on a single platform (IBM's WebSphere is an example). Chapters of the module also include several real life examples and case studies to highlight practical applications. Additional information and instructor material available from author website (www.amjadumar.com).