(Source: http://www.usdf.org/images/photos/about/about-dressage/Pyramid_of_training.jpg)
Dressage is a “building block” sport, meaning that certain aspects must be mastered before moving on. The training pyramid, pictured above, shows the basic progression of the necessary skills.
The bottom block, “Rhythm (With Energy and Tempo),” describes the importance of establishing steadiness and regularity in the horse’s gaits. The movement must be even, but contain energy.
The next block, “Relaxation (With Elasticity and Suppleness),” indicates that after rhythm has been achieved, the rider must aim for relaxation throughout their own and the horse’s body. Once both are relaxed, the horse’s movements become “elastic” and suppleness can be introduced.
The third block is “Connection (Acceptance of the Bit through Acceptance of the Aids).” At this point, the rider can begin to ask the horse for a more solid connection, because the relaxed and rhythmic horse can soften his back and move into the bridle without pulling or resisting the contact–accepting the aids.
The fourth block, “Straightness (Improved Alignment & Balance),” is actually quite difficult. Horses usually don’t naturally travel perfectly straight, so it takes extreme balance and acceptance to achieve this.
The final block is “Collection (Increased Engagement, Lightness of the Forehand, Self-Carriage).” Collection is at the top of the pyramid because it can only be achieved correctly when the block below are sufficient. Collection requires the horse to be engaged and “on the bit,” and carrying himself without leaning on the reins.
(
(Source: http://www.horseandlife.co.uk/userfiles/images/valegro_2767566b.jpg)
Dressage 
