Platform as a Service (PaaS) is a cloud computing model that provides a complete environment for application development and deployment, enabling businesses to simplify the process with flexible pay-as-you-go resource allocation. Key applications of PaaS include cloud migration, API development, IoT support, and automated software lifecycle management, making it especially advantageous for startups and small businesses by offering cost-effectiveness and accessibility. PaaS enhances efficiency and security in application development, unlocking new business possibilities in the digital landscape.