Platform as a Service (PaaS)
A Platform as a Service (PaaS) is a set of configurations, deployments & tools that allow developers to launch their applications into the cloud without having to manage the underlying infrastructure needed to run the application. To put it simply, a developer can focus on building their application and then upload it to a PaaS which will take care of getting it online and serving traffic. Without a PaaS a developer would need to launch their own servers, figure out a way to get their application on the server, and then be able to manage changes & updates to the application while it is live, running in production. PaaS systems ease the developer burden by giving you a template to run your applications. This speeds up time to market and results in fewer mistakes because PaaS systems are heavily tested and used. However, one of the trade-offs for using a PaaS may result in having less choice in how you deploy your applications. Usually, PaaS systems have a well defined and opinionated method for how they want you to run your application.
in other words
Building and managing applications in the cloud.