Pairwise testing is an effective test case generation technique that is based on the observation that most faults are caused by interactions of at most two factors. Pairwise-generated test suites cover all combinations of two therefore are much smaller than exhaustive ones yet still very effective in finding defects.
Resources
You can read more about this technique in many PAPERS and chapters of and even whole BOOKS published over the years.
Tools
There are many TOOLS that adopted and integrated pairwise testing as one of the test generation methods.