SOA, which stands for Service Oriented Architecture, is a software architecture style where generic services are provided to other components in the same architecture that provide more complex services based on the shared generic services. In the end, it is similar to a company´s shared services center.
Let´s imagine the following situation: A company that is operating in different countries has no shared services center at the moment. Therefore, basic HR and Finance activities, such as payroll and accounting are done individually in every country. By implementing a shared services center, the company can send all requests related to those activities to one single point of contact where the activities are executed. When the task is finalized, the results are sent back to the individual country. The individual countries then use the results, adapt them to country rules or their individual workforce and provide an additional, more sophisticated, or more individual service to their customers. SOA works in a very similar way. It allows to extract basic services from individual applications and bundles them in a shared services module instead. This shared services module then executes the tasks and provides the results back to the individual applications, which use them further.