The word dressage comes from the French verb "dresser" which simply means "to train." This is an excellent translation because Dressage is a program of suppling, balancing and obedience work that can prepare the horse for future work in any discipline.
Dressage is rooted in classical Greek horsemanship and was influenced by the athleticism needed from the mounts of knights and warriors of the Middle Ages. However, it was not until the Renaissance Era that dressage was recognized as a worthwhile pursuit for equestrian achievement. The great riding masters (generally still military personnel) of this period developed a logical training system which has changed little over the last hundred years. What has changed is the reason for the training. Originally, most dressage like movements were required on the battle field to evade enemies, or on the parade grounds to impress royalty; today, however, dressage is used as a basic training method to develop the athletic ability of the horse. This ability can be tested in formal dressage competitions.
Any horse can (and should) be schooled in dressage to maximize the horse's - and rider's - potential. The best dressage horses will have excellent basic gaits (walk, trot and canter) together with a good temperament and sound conformation. The horse naturally suited for dressage will have athletic gaits, be light on its feet and have the scope to take short, springy strides as well as free, long and swinging ones.
Do not worry if your horse does not possess all of these qualities. Let's be honest - the vast majority of horses in this world were not born with all these attributes. But this is why we have and need dressage. The basic training techniques used in dressage help to build these qualities in the horse. This does not happen overnight, but given proper instruction and patience, your horse will develop more of these qualities. Do not discount dressage if you are lucky enough to have a horse with the aforementioned qualities, however. Dressage allows you to build on the potential waiting to be unlocked in your horse.
Dressage demands that the horse display flexibility, submission, strength, impulsion, and many more qualities all while accommodating the weight of the rider. The trust and harmony which makes this possible are a tribute to the rider's ability and the horse's generosity.
Competitive dressage is ridden in a 20 x 40 or 20 x 60 meter arena, with lettered markers placed at specific points along the rail. Each rider performs a specific test. These tests are a set of predetermined movements that demonstrate the training and ability of the horse and rider.
There are many levels of tests for people at all levels of competition. The Introductory tests contain only simple movements done at the walk and trot. The most advanced series of tests are those ridden at the international level.
It is important to understand that dressage movements are not tricks. The most elegant movements may appear to be done simply for show. However, all are moves are natural and are performed by the horse in its natural environment. It is sometimes frustrating to watch your horse playing in the field and performing the most beautiful extended trot and knowing you could not do an average working trot in your lesson. With careful training, (and time and patience) the horse learns to duplicate these natural movements, willingly, on command, and with grace, while supporting the weight of the rider.