Software systems are an integral part of our daily life. Most people have had experience with software that did not work as expected. Software that does not work correctly can lead to many problems, including loss of money, time or business reputation, and, in extreme cases, even injury or death.

Software testing assesses software quality and helps reducing the risk of software failure in operation.

Software testing is a set of activities to discover defects and evaluate the quality of software artifacts.

These artifacts, when being tested, are known as test objects. A common misconception about testing is that it only consists of executing tests (i.e., running the software and checking the test results). However,
software testing also includes other activities and must be aligned with the software development lifecycle (see chapter 2).

Another common misconception about testing is that testing focuses entirely on verifying the test object.
Whilst testing involves verification, i.e., checking whether the system meets specified requirements, it also involves validation, which means checking whether the system meets users’ and other stakeholders’
needs in its operational environment.

Testing may be dynamic or static. Dynamic testing involves the execution of software, while static testing does not. Static testing includes reviews (see chapter 3) and static analysis. Dynamic testing uses different types of test techniques and test approaches to derive test cases (see chapter 4).

Testing is not only a technical activity. It also needs to be properly planned, managed, estimated, monitored and controlled (see chapter 5).
Testers use tools (see chapter 6), but it is important to remember that testing is largely an intellectual activity, requiring the testers to have specialized knowledge, use analytical skills and apply critical
thinking and systems thinking (Myers 2011, Roman 2018).
The ISO/IEC/IEEE 29119-1 standard provides further information about software testing concepts.