What it means
A web application does more than present pages: it lets people work with a process or data. Examples include preparing an estimate, assigning work or checking the status of an order. Some applications use accounts and permissions; others offer a single public task. The required behaviour, data and users determine the design.
Why it matters to your business
An application can remove repeated work, but it also introduces rules that must reflect how the business operates. Agree who may do what, which information is needed and what happens when a step fails. These decisions are often more important than the number of screens.
Following a service request
A repair business tracks requests in several spreadsheets. A possible application gives an authorized coordinator a shared list, clear statuses and an assignment step. The first version could focus on that flow; invoicing and customer accounts would remain separate questions until their value and requirements are understood.
Questions worth asking
Does every application need user accounts?
No. Access depends on the task and the sensitivity of the information. A public calculator and an internal order tool have different needs. Accounts and permissions should solve a concrete access requirement.
Can we build only the first useful part?
Yes. Define a complete, testable first workflow with clear limits. Keep later ideas visible, but distinguish them from the functions and acceptance criteria agreed for the first delivery.