As articulated previously, we are heading towards SDCEs that comprise software-defined compute (SDC), software-defined storage (SDS), and software-defined networking (SDN). The virtualization and containerization enable software-defined clouds towards workload-aware and elastic infrastructures. The maneuverability or programmability, consumability, accessibility, sustainability, and simplicity of software-defined clouds are greater compared to the inflexible infrastructures. There are new patterns (architecture and design) being introduced for cloud infrastructures and applications. The emergence of the cloud idea has brought in telling impacts on the application architectures. In this section, we will discuss how cloud application architectures differ from the legacy application architectures.