What is a correct headset?

Figure 1: A correct headset.
This head position is ideal for a horse to correctly carry itself in order to achieve collection. While the horse isn't on the vertical, you can see that it's relaxed at its poll (The poll is directly behind the horse's ears.) and is able to stretch forward into the bridle. Without this, you can not have a horse who is able to engage it's hind end and move upwards into the shoulder. In order to achieve collection, you must educate your horse's body and mind while understanding that it is going to take steps; true collection cannot be obtained by force.

Figure 2: Commonly mistaken as a correct head set.
This head position isn't terrible, but it's still very much incorrect. Even though the horse is on the vertical, it has a broken neckline (The poll is not the highest point on the neck.) that is creating tension on the poll. This means that the horse can not stretch out in order to engage, making it extremely difficult to correctly carry itself. This head position is a clear indicator that the horse is evading contact due to rider error or not correctly (Not forcing it onto the horse.) teaching the horse how to use its body. With that being said, 9/10 you will see this being called correct when it's just another form of false collection.

Figure 3: A very incorrect headset.
This position is also known as a horse being kept behind the vertical (BTV) and can even be considered rollkur, if forced for an extended amount of time. The head itself will be sucked back towards the neck creating a more noticeable broken neckline. This alone creates immense tension at the poll which causes discomfort and even pain for the horse. It's literally impossible to obtain proper collection while in this position because the horse's body has to accommodate for the curves of the neck by dropping the back and shoulders. This position can only be obtained by extreme rider error, lack of (correct) training, or just plain cruelty. It should also be noted that rollkur is considered abusive and is illegal (Hardly ever enforced because the show world is extremely corrupt.) in many showing circuits.
____________________________________________________

_{Image © SynBrittany}