A Web application (Web app) is an application program that is stored on a remote server and delivered over the Internet through a browser interface.
A web application is any application that uses a web browser as a client. The application can be as simple as a message board or a guest sign-in book on a website, or as complex as a word processor or a spreadsheet.
Web services are Web apps by definition and many, although not all, websites contain Web apps. According to Web.AppStorm editor Jarel Remick, any website component that performs some function for the user qualifies as a Web app:
“I always ask myself, ‘Does it do something?’ Even if it only does something small and specific, it’s still a web app. Google’s search engine is a web app, yet its root concept is hardly different from a phone directory that enables you to search names or numbers.”
Within the mobile computing sector, Web apps are sometimes contrasted with native apps, which are applications that are developed specifically for a particular platform or device and installed on that device. However, the two are not mutually exclusive because many applications contain elements of both native and Web apps. Programs that combine the two approaches are sometimes referred to as hybrid applications.