Is an investigation conducted to provide stakeholders with information about the quality of the software product or service under test.
Software testing is an activity to check whether the actual results match the expected results and to ensure that the software system is Defect free. It involves execution of a software component or system component to evaluate one or more properties of interest. Software testing also helps to identify errors, gaps or missing requirements in contrary to t he actual requirements. It can be either done manually or using automated tools. Some prefer saying Software testing as a White Box and Black Box Testing.
On any typical work day, you will be busy understanding requirement documents, creating test cases,executing test cases, reporting and re-testing bugs, attending review meetings and other team building activities.
Testing is important because software bugs could be expensive or even dangerous. Software bugs can potentially cause monetary and human loss, and history is full of such examples.