Ad-hoc testing is the process of creating tests based on a need to test. These tests are not created as part of a set plan or to test specific features but rather to ensure that specific areas of the product work correctly. It is also performed as part of regression testing to ensure that new patches and fixes do not cause any issues with the current version of the product.
A tester must be willing to challenge any idea, no matter how good or absurd. One of the best ways to test your ideas is through Adhoc testing, which is a great way to discover new issues and risks with minimal effort. It allows you to take a more creative approach and try new things to find a problem by not formalizing the process.