A web application is a website that has advanced business-specific features and capabilities..
Examples of Business-Specific Features and Capabilities:
These usually involve a sequence of visitor interactions whereby the registrant validates their email address, answers a series of questions, agrees to legal terms, pays a registration fee, etc.
These usually involve presenting a series of questions to site visitors; multiple choice, open-ended free text, true/false, etc. Responses are typically saved to a database with reports providing summary statistics.
Product catalogs and shopping carts typically include business-specific features and capabilities.
Almost any useful web application will take at least 2-4 weeks, and frequently much longer, to design, develop, test, and deliver. Consequently, the starting price is usually around $6,000.