It uses web technologies and can progressively add features such as installation or offline handling when the browser and implementation support them. The exact capabilities depend on the application and environment.
An app-like presentation does not supply a security boundary by itself. Authentication, network exposure and access to underlying tools remain separate design responsibilities.
ELI5
Think of a website that can behave more like an installed tool while still using browser technology.
For example, a phone can open a web-based terminal interface, while the application still needs its own appropriate protection for remote access.
Does every progressive web app work offline?
No. Offline behavior requires suitable implementation and depends on what the app must access.
Does installing a PWA make its server private?
No. Installation and server access control are separate concerns.
