Exploratory software testing is a powerful and fun approach to testing. In some situations, it can be orders of magnitude more productive than scripted testing. I haven’t found a tester yet who didn’t, at least unconsciously, perform exploratory testing at one time or another. Yet few of us study this approach, and it doesn’t get much respect in our field. It’s high time we stop the denial, and publicly recognize the exploratory approach for what it is: scientific thinking in real-time. Friends, that’s a good thing.

• As its name implies, exploratory testing is about exploring, finding out about the software, what it does, what it doesn’t do, what works and what doesn’t work. The tester is constantly making decisions about what to test next and where to spend the (limited) time. This is an approach that is most useful when there are no or poor specifications and when the time is severely limited.
• Exploratory testing is a hands-on approach in which testers are involved in minimum planning and maximum test execution.
• The planning involves the creation of a test charter, a short declaration of the scope of a short (1 to 2 hour) time-boxed test effort, the objectives and possible approaches to be used.
• The test design and test execution activities are performed in parallel typically without formally documenting the test conditions, test cases or test scripts. This does not mean that other, more formal testing techniques will not be used. For example, the tester may decide to us boundary value analysis but will think through and test the most important boundary values without necessarily writing them down. Some notes will be written during the exploratory-testing session so that a report can be produced afterward.
• Test logging is undertaken as test execution is performed, documenting the key aspects of what is tested, any defects found and any thoughts about possible further testing.
• It can also serve to complement other, more formal testing, helping to establish greater confidence in the software. In this way, exploratory testing can be used as a check on the formal test process by helping to ensure that the most serious defects have been found.
• Exploratory testing is described in [Kaner, 2002] and [Copeland, 2003] other ways of testing in an exploratory way (‘attacks’) are described in [Whittaker, 2002].