Software Testing plays a crucial part in the modern software development process. It is usually associated with the terms, ‘validation’ and ‘verification’. A fine line lies between testing too much which is not ideal from the business, cost and time perspective; and not testing enough which negatively affects the quality of the final product, ultimately resulting in higher costs (fixing on production cost more and has a direct impact on customers). Many factors must be taken into consideration when implementing effective test strategy. The purpose of this thesis is to show the application of specific test strategies usable in software testing. This Master thesis provides an insight into the various phases of software testing including system, system integration, regression, user-acceptance, automation and performance testing. The way how and when the tests are executed depends on the software development type as well.