Selenium is an open-source framework specifically designed for web application automation testing. It supports various browsers and languages like Java, C#, and Python. While other tools like Appium, TestNG, and Cucumber have their specialties, Selenium stands out for web automation.

Residual risk is the risk that remains after all risk response, mitigation, or prevention activities have been implemented. It represents the remaining threat even after you've taken measures to reduce the severity or likelihood of the adverse event.

Cyclomatic Complexity is a white-box testing metric used to determine the complexity of a program. It calculates the number of linearly independent paths through a program's source code. A higher complexity score can indicate areas of the code that might be riskier or overlooked during testing, thus requiring more thorough testing.

Regularly updating and maintaining an automated test suite is crucial to ensure that the suite is always in sync with the current version of the application. As software evolves, test cases that were once relevant might become obsolete, and new test scenarios may arise. Maintenance ensures the suite remains effective and reflective of current needs.

Stubs are used in incremental integration testing as placeholders for modules that have not yet been developed. They simulate the behavior of these missing modules and allow testing to continue in the presence of incomplete components.

The "Pesticide Paradox" principle states that just as pesticides become ineffective when pests develop resistance, similarly, test cases lose their effectiveness if they are not regularly reviewed and updated. New defects can't be found when using the same tests repeatedly.

Usability Testing ensures that the designed application is user-friendly, intuitive, and easy to use. Especially for elderly users who might not be familiar with modern tech conventions, ensuring the app's usability is crucial to prevent any potential frustration or challenges during their interaction.

Postman is a versatile tool designed for API testing. With microservices, the emphasis is often on ensuring API contracts and interactions are reliable. While tools like JUnit and Selenium are great for unit and UI tests respectively, Postman offers the flexibility required for varied microservices.

Defect Detection Percentage (DDP) is a vital metric that calculates the ratio of the number of defects detected to the total number tested. It provides insight into the efficiency of the testing process, giving an understanding of how well the testing phase is identifying issues.

The "think-aloud" method is used in Usability Testing. Participants are asked to speak their thoughts aloud while they perform tasks, providing insights into their cognitive processes, decision-making, and how they navigate and interact with the interface, highlighting potential usability issues.

"Unit Testing" focuses on the smallest unit of the software design (like functions, methods, or classes). Each unit is tested in isolation to discover any discrepancies between its expected and actual outcomes.

UI elements can change their position, style, or other properties frequently. Using dynamic XPath locators allows test scripts to identify elements based on their unique relationships and properties rather than fixed coordinates or attributes that might change. This method ensures greater adaptability and reduces the chance of script failures due to minor UI adjustments.