Four Types of Defensive Techniques

[Sanko]

ITF Taekwon-Do's defensive techniques can be divided into four types,
namely hard blocks, soft blocks, body shifting and guards.

Hard blocks generally used to hurt your opponent's attacking limb.
Soft blocks are generally used to deflect an attack or unbalance an
opponent. Body shifting is used to avoid clashing with an attacker or
to blend with the movement of an attacker. Finally, guards are used as
a type of buffer or fence between your person and an attacker.

You can a more thorough exposition at the Soo Shim Kwan blog:
http://sooshimkwan.blogspot.com/2010/11/defensive-techniques-in-itf-taekwon-do.html

Regards,

Sanko