A web application is a hierarchical set of folders containing scripts that will create:
These folders are structured according to the standard specified by the application server where the application is deployed and executed.
The application is created via a node web bundler.
Web applications are of the following types:
A frontend (known also as Presentation-oriented application) generates interactive web pages containing various types of markup language (HTML, XHTML, XML, and so on)
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Service-oriented: A service-oriented web application implements the endpoint of a web service. Presentation-oriented applications are often clients of service-oriented web applications.
Software is commonly delivered as a service: called web apps, or software-as-a-service. The twelve-factor app is a methodology for building software-as-a-service apps. You can configure a service using environment variables only for instance.