The half halt is one of the least understood concepts in Dressage. Ask 10 different riders... even ask 10 different trainers... what it means, and you are likely to get 10 different answers. (Read my explanation of the half halt here.)
In truth, there are several different types of half halts. And riders need to have a good understanding of all of them! (Read all about the different types of half halts here.) Riders also need to know which particular type of half halt is needed for their particular horse at that particular moment.
The wrong type will not produce the results you are looking for. A very common example that I often see is riders on the more laid back or quiet type of horse thinking that because their horse is not getting strong or heavy, they do not need half halts. And when they are told to half halt, they invariably use the wrong type of half halt for their horse's needs.
Too much "whoa" in the equation of aids actually disengages the lazier type of horse's hind legs, rather than engaging them. This type of horse very often needs half-goes instead! Read on to learn all about the half-go!