Gothenburg the non-exclusive right to publish the Work electronically and in a

Context: Exploratory Testing has experienced a rise in popularity in the industry with the emergence of agile development practices, yet it remains unclear, in which domains and how it is used in practice. Goal: To study how software engineers understand and apply the principles of exploratory testing, as well as the specific advantages and difficulties they experience. Method: We conducted an online survey in the period June to August 2013 among Estonian and Finnish software developers and testers. Results: Our main findings are that the majority of testers, developers, and test managers using ET, (1) apply ET to usability-critical, performance-critical, security-critical and safety-critical software to a high degree; (2) use ET very flexibly in all types of