What is Exploratory Testing (ET)? I am asked this every once in a while and I hear a wide range of ideas as to what it is. This is one of those topics where Wikipedia doesn't really help much.
For some, ET is just "good" testing and the reason we say "exploratory" is to distinguish it from bad testing practices. Unfortunately, bad, lazy, haphazard, thoughtless, incomplete, and incompetent testing is quite popular. I won't go into the reasons or supporting evidence for this disgraceful blight on the Software Development industry at this time. Suffice it to say, I don't want to be mixed in with that lot either, so I am happy to describe what I do as something different - something that is far more successful and rewarding when done well.
Okay, so if ET = [good] testing, what is testing then? According to Cem Kaner, "software testing is a technical investigation conducted to provide stakeholders with information about the quality of the product or service under test." This definition took me a while to absorb but the more I thought about it the more I found it to be a pretty good definition.
If you ask Elisabeth Hendrickson, she would say that "a test is an experiment designed to reveal information or answer a specific question about the software or system." See, now I really like this definition! I studied Science in university and I love the way this definition reminds me of the Scientific Method. The more I learn about testing software, the more I find similarities with doing good Science. (By the way, if you want to learn more about how to do good testing, I highly recommend you read up on the Scientific Method. So much goodness in there!)
So, is that all there is to it? Testing = Science, blah blah blah, and we're done? Um, well, no, not really. ET has its own Wikipedia page after all!