Software testing should be distinguished from the separate discipline of software quality assurance, which encompasses all business process areas, not just testing.

         There are many approaches to software testing, but effective testing of complex products is essentially a process of investigation, not merely a matter of creating and following routine procedure. One definition of testing is "the process of questioning a product in order to evaluate it", where the "questions" are operations the tester attempts to execute with the product, and the product answers with its behavior in reaction to the probing of the tester [citation need].

         Although most of the intellectual processes of testing are nearly identical to that of review or inspection, the word testing is connected to mean the dynamic analysis of the product—putting the product through its paces. The quality of the application can, and normally does, vary widely from system to system but some of the common quality attributes include capability, reliability, efficiency, portability, maintainability, Compatibility and usability. A good test is sometimes described as one which reveals an error; however, more recent thinking suggests that a good test is one which reveals information of interest to someone who matters within the project community.

White box and Black box testing
         White box and black box testing are terms used to describe the point of view a test engineer takes when designing test cases. Black-box being external views of the test objects where as white box being an internal view of the test objects. In recent years the term grey box testing has come into common usage. Typical grey box tester is permitted to set up or manipulate the testing environment, like seeding a database, and can view the state of the product after his actions, like performing a SQL query on the database to be certain of the values of columns. It is used almost exclusively of client-server testers or others who use a database as a repository of information, but can also apply to a tester who has to manipulate XML files (DTD or an actual XML file) or configuration files directly. It can also be used of testers who know the internal workings or algorithm of the software under test and can write tests specifically for the anticipated results.

Testing Levels
         Component testing tests the minimal software item that can be tested. Component integration testing exposes defects in the interfaces and interaction between integrated components. System testing tests an integrated system to verify that it meets its requirements.