Definition

Exploratory testing is an approach to software testing that is concisely described as simultaneous learning, test design and test execution.

Comment

Exploratory testing is often thought of as a black box testing technique. Instead, those who have studied it consider it a test approach that can be applied to any test technique, at any stage in the development process. The key is not the test technique nor the item being tested or reviewed; the key is the cognitive engagement of the tester, and the tester's responsibility for managing his or her time.

Also see: Ad-hoc testing, Black box test