This document provides an introduction to service oriented architecture (SOA). It defines SOA as an architectural model that enhances efficiency, agility and productivity through a collection of loosely coupled services and connections. The document outlines the benefits of SOA from both technology and business perspectives, such as improved integration, flexibility and global sourcing. Challenges of adopting SOA include the early adoption of supporting technologies, organizational changes and complex program management. The document concludes by stating that modern SOA is based on web services and lists some programming languages used to implement SOA.