Platform as a Service - cloud platform that provides development tools and infrastructure so you can focus on building applications. Like renting a fully equipped kitchen where you just cook without worrying about maintaining appliances.
Heroku is PaaS that lets developers deploy applications without managing servers, databases, or operating systems.
All provide managed application platforms to deploy code without managing servers. Elastic Beanstalk, App Service, and App Engine are common PaaS options for web apps and APIs. OCI offers PaaS capabilities through its application platform services (often grouped as APaaS), such as Visual Builder for app development and other managed app services depending on workload.