what is the testing approach for web based application?

Why testing Web Applications is different?
Testing web applications is different because of many factors scenarios affecting the performance and user experience.
Web applications can typically cater to a large and a diverse audience. Web Applications can also be exposed to wide range of security threats. Web applications may open up illegal points of entry to the databases and other systems holding sensitive information.


Test Approach is a part of test plan.Basically this is what you want to test about the application.

1.what are the types of testings that we are going to perform on that application.let us say

1) Functionality Testing
2) Usability testing
3) Interface testing
4) Compatibility testing
5) Performance testing
6) Security testing

http://www.softwaretestinghelp.com/web-application-testing/

2.