Ad hoc testing
Ad hoc testing is a commonly used term for software testing performed without planning and documentation. The tests are intended to be run only once, unless a defect is discovered. Ad hoc testing is a part of exploratory testing, being the least formal of test methods.
Strengths of Ad Hoc Testing
One of the best uses of ad hoc testing is for discovery. Reading the requirements or specifications (if they exist) rarely gives you a good sense of how a program actually behaves. Even the user documentation may not capture the “look and feel” of a program. Ad hoc testing can find holes in your test strategy, and can expose relationships between subsystems that would otherwise not be apparent.
For more on When is Ad Hoc Testing NOT Appropriate? and Techniques for Ad Hoc Testing see here.
Few interesting resources on Ad hoc Testing:
How to Measure Ad Hoc Testing?
Measure Ad-hoc Testing
Ad Hoc Software Testing - A perspective on exploration and improvisation.
Ad Hoc Software Testing
Is Adhoc Testing in anyway similar to Smoke Testing?
Ad hoc Testing
Difference between exploratory and Ad hoc testing.
Difference Exploratory & Ad hoc Testing
Exploratory Versus Ad hoc testing.
Exploratory VS adhoc testing
Exploratory testing is also known as Ad hoc testing.
Exploratory Testing Article