This book explains in detail the basic concepts, strategies used and issues involved in planning, designing and executing test cases for testing of application software and ensuring the quality of software developed. It provides a detailed discussion on software testing and why is it an indispensable part of software development. This book also highlights the testing techniques and various strategies used for the same. Strategies of verifying and validating software according to specifications and customer expectations have also been discussed along with the details of how to build test plans and test cases. Various issues related to the software quality standards have also been explained in simple English with the help of examples and illustrations. Topics like debugging tools and external sources of error have also been treated in a simple and effective way.