Companion Dog (CD) refers to a title offered by the American Kennel Club for dog obedience. Other kennel clubs also offer similar CD titles. To earn an AKC CD title, a dog must receive a qualifying score in the Novice obedience class at three separate, AKC-licensed, obedience trials, and by three different judges. The American Kennel Club (or AKC) is the largest registries of purebred dog pedigrees in the United States. ... Obedience is the willingness to follow the will of others. ...
Dogs which receive three qualifying scores competing in the more challenging Open class at three different obedience trials, and by three different judges, can be awarded the AKC Companion Dog Excellent (CDX) title.
External Links
AKC Titles and Abbreviations (http://www.akc.org/events/titles.cfm)
Dogs compete in a hierarchical fashion at each show, where winners at lower levels are gradually combined to narrow the winners until the final round, where Best in Show is chosen.
Strictly speaking, a dog show is not exactly a comparison of one dog to another, it is a comparison of each dog to a judge's concept of the ideal specimen as dictated by the breed standard; based on this, one dog is placed ahead of another.
Show dogs have a registered name, that is, the name under which they are registered as a purebred with the appropriate kennel club, and a call name, which is how their owners talk to them.