In this photo collage you will see a series of dogs. Each dog and group were bred for different jobs and purposes.
The first group is the "catch dogs". (Boxers, Pit Bulls, Rhodesian ridgebacks, Catahoulas, etc) These dogs were bred to kill and help take down animals such as hogs. Hunters will use them to help hold them in place until he arrives.
The second group is the "Lap dogs". (Shitzus, Pomeranians, malteses, Pugs, etc) These dogs were bred for royalty and sat in the thrown with the royals.
The third group is the "Hunting dogs". (Labs, Golden Retrievers, Weimaraners, Basset Hounds, etc) These dogs were bred to help their owners hunt prey. Depending on the breed, some are used for bird hunting to retrieve the birds and some are used for tracking.
The fourth group is the "protective dogs" (German Shepherds, Belgian Malinois, Rotties, Cane Corsos, etc). These dogs were bred to protect their owner and the land.
It is crucial to know your dog's background and what they were bred to do. If you are not fulfilling the job for your dog, you will need to make one for him. Otherwise, he will create his own job (digging, growling, lunging, jumping, protecting objects, etc)
Another reason it is crucial to know your dog's background is for learning what specific areas you will need to focus on in order to avoid bad habits from forming. Ex: Pit Bulls, Boxers, etc were bred to help take down animals, so they would require more proper socialization with animals. Or, shitzus, Malteses, etc would require work with jumping since they were bred as lap dogs. Labs were bred to track and retrieve so they would need more walking or running along with a lot of focus work. Protective breeds can easily get overprotective of there owners and property, so making sure these breeds respect you and your decisions is crucial to making sure your guests stay safe.
Always have a solid background of knowledge while picking out a family pet. This will make it easier for everyone to adjust to each other.