TL;DR
This post defines test technique. Definition is aligned with Black Box Software Testing Foundations course (BBST) created by Rebecca Fiedler, Cem Kaner and James Bach.
Definition
Test technique is like a recipe. It tells you how it puts together some ingredients. Then you vary it to suit your needs.
A technique tells you how to do several (rarely all) of these:
- analyze the situation
- model the test space
- select what to cover/not cover
- determine test oracles
- configure the test system
- operate the test system
- observe the test system
- evaluate the test result
This list is very helpful resource when you need to tell your testing story what should be done to test some feature. You will be able to give more precise estimate how many resources (time, testers, equipment) you need to test something.