checklist-based testing

An experience-based test design technique whereby the experienced tester uses a high-level list of items to be noted, checked, or remembered, or a set of rules or criteria against which a product has to be verified.

In simple English:

You have a very high level checklist and you check items off it as you test. 

Field notes:

1. Note that this is not the same as exploratory testing. 

2. The check list is usually the most basic version of a test case.

3. This method relies heavily on the experience of the tester.  

4. The experience of the tester with the system under test is more important than the general test experience of the tester.

5. The checklist does not usually support recording extensive test results.