What is the difference between working, collected, medium, and extended gaits in dressage?

Working, collected, medium, and extended gaits describe four different expressions of each gait that together demonstrate the horse's training development and its ability to adjust its stride length and energy while maintaining quality and rhythm. Working gaits are the natural, active versions of each gait for a horse in early training — the trot and canter in which the horse moves forward with energy and regular rhythm but without the specific demands of collection or extension. Working gaits are not lazy or minimal but active and forward, representing the appropriate expression of the gait for a horse at Training and First Level. Collected gaits require the horse to carry more weight on its hindquarters, shorten and elevate its stride, and show increased engagement and cadence compared to working gaits — the stride is shorter but more active and expressive, and the horse's overall balance is more uphill. Collection first appears in the tests at Second Level and develops in depth and quality through the upper levels. Medium gaits demonstrate the horse's ability to extend its stride moderately beyond the working stride, covering more ground per stride while maintaining the rhythm and quality of the gait — the medium trot is between the working and extended expressions and demonstrates the beginning of the horse's ability to show different lengths of stride within the same gait. Extended gaits represent the maximum lengthening of the stride that the horse can achieve while maintaining rhythm and self-carriage — the hind legs reaching as far forward as possible in their moment of extension and the front legs reaching forward to meet them, with the horse showing maximum ground coverage in each stride. The ability to move freely between all four expressions while maintaining quality reflects the full development of the Training Scale's qualities.