This chapter examines the concept of Service-Oriented Architecture (SOA) in conjunction with the Web Services technology as an implementation of the former’s design principles. Following a brief introduction of SOA and its advantages, a high-level overview of the structure and composition of the Web Services platform is provided. This overview covers the core Web services specifications as well as features of the extended architecture stack, which together form a powerful and robust foundation for building distributed systems. The chapter concludes with a discussion of the scope of applicability of SOA and Web services. The overall goal of this chapter is to portray the key assets of the presented technologies and evaluate them as tools for handling adaptability, portability, and interoperability issues that arise in modern business environments.