Exploratory testing is the most efficient and effective approach to testing software. It produces useful results from the first hours of testing, and finds the biggest bugs faster than any other approach. Furthermore, it finds bugs that other approaches won’t find at all.
Exploratory testing is not constrained in any way. The objective is to expose information that is of value to stakeholders and assess the quality of the software. Exploratory testers are always looking for what we term “emergent behaviors”, which are behaviors that could not have been predicted prior to the start of testing.