SOA (Service Oriented Architecture) is a method of developing programs as interlinked services that can be reused and expanded to provide additional functionality. It allows for more flexibility and integration between business processes and IT systems. SOA distributes software as services stored centrally and accessed through thin clients like web browsers. It provides benefits like easier alignment of IT with business needs and integration of partner/customer services. Requirements include combining concepts of building/acquiring services and maximizing available resources and commercial software. SOA facilitates management and integration of different software after mergers by allowing easier updating and modification of services.