Exploratory testing is basically Black Box testing, we do not need to worry about internal coding of the software while performing the Exploratory Testing. In simple word Exploratory Testing is all about simultaneously Learning, Test Design and Test Execution. Means here tester first learn about the software then write the test cases or test scenario for it and then execution of those written scenarios all this at on the fly. And this learning about the software needs not to be in sequence. Means tester may choose any feature any module and start learning about it. Tester has the freedom to do whatever he wants; this testing totally depends on the tester creativity, thinking and domain knowledge of the Tester.
Why do we calls exploratory testing is depends on tester creativity and thinking? so if you have these question in your mind then the answer is , in Exploratory testing we do not write test cases in advance here tester learn about the features and about the module , write the test cases for it. So it totally depends on how much skilled and quick learner tester are. Where as in other type of testing they write the test cases in advance then they just execute it on the software which is we can called it non – thinking activity just need to follow the steps written in the test cases.