Keeping in view the environment and behaviour of web-based systems, we face many challenges while testing them. These challenges become issues and guidelines when we perform testing of these systems. Some of the challenges and quality issues for web-based system are discussed here:

Diversity and complexity: Web applications interact with many components that run on diverse hardware and software platforms. They are written in diverse languages and they are based on different programming approaches such as procedural, OO, and hybrid languages such as Java

Server Pages (JSPs). The client side includes browsers, HTML, embedded scripting languages, and applets. The server side includes CGI, JSPs, Java Servlets, and NET technologies. They all interact with diverse back-end engines and other components that are found on the web server or other servers.

Dynamic environment: The key aspect of web applications is its dynamic nature. The dynamic aspects are caused by uncertainty in the program behaviour, changes in application requirements, rapidly evolving web technology itself, and other factors. The dynamic nature of web software creates, challenges for the analysis, testing, and maintenance for these systems. For example, it is difficult to determine statically the application's control flow because the control flow is highly dependent on user input and sometimes in terms of trends in user behavior over time or user location. Not knowing which page an application is likely to display hinders statically modelling the control flow with accuracy and efficiency.

Very short development time: Clients of web-based systems impose very short development time, compared to other software or information systems projects (eg. an e-business system, sports website, etc).

Continuous evolution: Demand for more functionality and capacity after the system has been designed and deployed to meet the extended scope and demands, that is, scalability issues.

Compatibility and interoperability: As discussed, there may also be compatibility issues that make web testing a difficult task. Web applications often are affected by factors that may cause incompatibility and interoperability issues. The problem of incompatibility may exist on both the client as well as the server side. The server components can be distributed to different operating systems. Various versions of browsers running under a variety of operating systems can be there on the client side. Graphics and other objects on a website have to be tested on multiple browsers. If more on than one browser will be supported, then the graphics have to be visually checked for differences in the physical appearance. The code that executes from the browser also has to be tested. There are different versions of HTML. They are similar in some ways but they have different tags which may produce different features.