Software architecture is a high-level structure that lays out the overall design and organization of a software system. It includes defining the components, relationships, and interactions between different modules or layers of the system. Software architecture also involves making decisions about the system's key characteristics such as performance, security, scalability, and maintainability. The goal of software architecture is to create a robust, flexible, and efficient system that meets the requirements of its users. Various architectural patterns and styles, such as client-server, microservices, and layered architecture, can be used to design software systems.