What ?

Exploratory testing is an approach to software testing that is concisely described as simultaneous learning, test design and test execution.
Exploratory testing seeks to find out how the software actually works, and to ask questions about how it will handle difficult and easy cases.
The quality of the testing is dependent on the tester’s skill of inventing test cases and finding defects. The more the tester knows about the product and different test methods, the better the testing will be.

Why ?

Because it leverages human intelligence, Exploratory Testing gives you a broader and deeper view than any automated test could.

Exploratory testing involves exploration without using a predefined sequence of steps.

These are the main benefits of exploratory testing :

• Helps you expose defects that automated and manual testing miss
• Helps many different team members collaborate to expose more types of defects
• Lets you find functional defects when automated testing is not viable

Basically, it will help you to provide high quality software. Exactly what a software craftsman wants for his clients.

How ?

• Organize an exploratory testing session
  • Invite
    • Team members
    • Business/domain experts
  • Set up the required equipments
  • Prepare required accounts (users)
  • Run the session
    • Report everything
  • After the session
    • Write the missing tests based on the report

Resources

• Exploratory Testing Tutorial: Process, Techniques & Examples
• The right way to run exploratory testing in an agile environment
• The testing manifesto
• Agile tests pyramid
• Agile testing quadrants