I define a backyard breeder as someone who breeds their pet quality dog. They're not involved in conformation or performance events. They may be motivated by money or simply by the novelty of the experience. The litter may be planned or accidental but in either case, very little thought, planning or testing has gone into the breeding. A responsible hobby breeder is someone with a passion for their breed; involved in conformation and/or performance events. Their dogs are pets, too; typically bred and raised in their home. These breeders devote many, many hours to educating themselves and the public about their breed. A commercial breeder or puppy mill is someone who breeds dogs for profit. This may occur in a big commercial kennel or it may occur in someone's home. They generally keep many dogs (and sometimes many breeds) and the dogs are usually not shown, as this would cut into their profit margin. Health screening is also kept to a minimum for the same reason.