The application code usually sits on a remote server and the user interface is presented at the clients' WWW browser. Web applications are by their nature platform independent and leverage off the accessiblity of the Web. There are many advantages for using the Web as the application interface. The most important being wide accessibility, because they leverage off of the accessibility of the Web by using HTTP to bridge application and interface. They also support collaborative work since many users share a single program and its associated data.
Applications are self-documenting.
The hypertext model of the Web makes it simple for Web interfaces to contain embedded documentation and links to auxiliary material. Finally, applications integrate seamlessly with the Web. Interfaces to Web applications may be accessed as regular Web pages. Although it is too early to see large commercial Web applications, there is no shortage of early efforts of both a practical and fun nature. There are spreadsheets, clocks, scrolling newswires, stock-commission calculators, financial graphing applications, educational supports, and, of course, games from solitaire to missile command.