Techniques
Techniques are an extension to your skills, that allow you to use your skills in new ways. There are three types of techniques, and explaining these types is a good way of understanding what techniques are in Strikermechanica.
Enabler Techniques
By putting ranks on an enabler technique, you unlock a new way of using a skill that was not previously available. The technique is still related to the skill its extending, but its a use that requires a special preparation or training. the simple rule is that you cannot use an enabler technique, unless you have at least one rank on it.
Specialiser Techniques
A specialiser technique usually represents using the parent skill in a particular circumstance, or it's a particular area of knowledge. You can use a specialiser technique without putting ranks on it. Its just that it provides no additional benefit and your roll is that same as that on the parent skill. Techniques based on a particular class of weapons, like Wpn-Flechettes, are good examples of specialiser techniques.
Facilitater Techniques
A facilitator technique is more or less a half-way point between an enabler technque and a specialiser technique. You can use a the actiona associated with the facilitator technique without having ranks on the technique, but you are at -3. This is similar to trying to use a qualifier skill without a qualifying rank.