The above writeups do a servicable job of explaining the mechanics involved in the execution of gedan barai as one of the kihon - or one of Karate's basic techniques.

However, when they refer to this technique as a block, they emasculate it to such a degree that a lower-level student might miss out on one of the most important and effective techniques that Japanese martial arts has to offer.

The cold, hard truth is that no technique in Karate can be viewed solely as a blocking technique; everything can, and should, cause damage to your opponent. Latter-day revisitations of the theory behind Karate basics notwithstanding, every Karate technique is active, aggressive, and dangerous. It is currently in vogue to teach beginners that Karate is for peaceful purposes only, or a way of getting in touch with your softer side, or some other hogwash, but anyone who studies this martial art long enough to learn a few kata ought to understand the meaning behind the basic techniques.

Gedan barai is best interpreted as a throwing technique. The kata Heian shodan, generally taught first in most Karate schools, presents several throwing variations that employ Gedan barai. The most basic of these involves grabbing and pulling your opponent's belt with your drawing hand while you push your blocking hand (for want of a more accurate term) against your opponent's face or neck as you step behind his leg to trip him and push him to the ground. All this in the very first move of the very first kata! Other throws - hip throws and shoulder throws - can be found in the same kata all using Gedan barai.