A web application is interactive software you use through a browser to actually do something, not just to read. Online banking, a project board, a booking system: you log in, enter data, get results, and the screen responds to what you do. That two-way interaction is what separates a web app from a plain website.
The difference is a bit like a library versus a workshop. A standard website is the library: you browse and read what is on the shelves. A web application is the workshop: you go in to make, change and manage things. Gmail, Trello and online accounting tools all fit this mould, and they are delivered as web-based software so nothing needs installing. When the whole app loads once and updates in place without full page reloads, it is often a single-page application.
Because they run in the browser, web apps work across Windows, Mac, phones and tablets, and updates reach everyone instantly through the server. That makes them the natural shape for tools a whole team relies on day to day.
The trade-off is that a web app leans on a connection and a server. Lose the network and most of it stops, and the work of keeping that server fast, backed up and secure does not go away the way it might with a simple site. There is also a grey area worth knowing: many web apps now cache enough to keep working offline for a while and can be installed to a home screen, which blurs the old line between a web app and a native one.
At TopDevs we build web applications that handle a client’s real work, from internal dashboards to customer portals, fast and reliable on every device.
