It's a developed application made to be on browser like ( Google Chrome ) This application is written in many programming languages " python, php, perl, ruby" and developed by web application framework.
Why would you need web applications ?
web applications make research easier and more convenient.
web applications also gather and analyze and save the data provided by the website users and make it available : . At the beginning the input data was sent to the employees as HTML model emails or as CGI application, however if web applications were used the data models are saved directly in the data base.. the same used in case of extracting the data for preparing reports based on the web in order to analyze it ..
for example : the banking services' web pages, stores' sales web pages, surveys and users feedback models. .It also provides updating the websites' content that changes continuously as web applications save lots of time and effort consumed by the designer as the content creators for example news editors feed the web application with content which is being updated automatically in .