Congratulations! You have been selected by NBC to judge a dog show: The National Dog Show presented by Purina on NBC this Thanksgiving Day.

To be just like the judges you see working in the ring, you will need to know what specific job each breed was developed to perform for their people. You will need to know and understand the written standard, which describes the ideal specimen of that breed. You will need to evaluate the dog’s physical traits, movement, personality and more.

Or you can pick the dog you like for whatever reasons you choose: It’s cute, you love the hairstyle, you love its personality, the color is nice. It’s the dog that you would like to take home with you.

You’ll have plenty to select from: Over 150 breeds and varieties will parade through your home on Thanksgiving, most of them dogs that you’ll never see walking in the park. There will be something for everyone in the family, for every lifestyle imaginable.

The true purpose of dog shows is to evaluate breeding stock, to find the best dogs to produce the next generations of healthy family and working dogs. In the ring, it can be a challenging task. The differences between dogs can be subtle. Judges must understand form and function: What specific job a breed was developed to perform, and what physical traits and structure will best accommodate that job.

The ideal specimen of every breed is described in its standard, a written description relating form to function, describing general appearance, movement, temperament, and specific physical traits such as height and weight, coat, colors, eye color and shape, ear shape and placement, feet, tail, and more.

If your opinion in your living room is different from the official judge inside the ring, just remember: That judge gets an “up close and personal” perspective. They examine those traits and get to feel the structure and conditioning under all that hair. They also get to watch the dogs move from the best vantage point: in the ring. They put all those observations together and determine which of the dogs in the ring that day best resembles that ideal specimen described in the standard.

Have fun seeing how your choices compare to the judges on “The National Dog Show presented by Purina.”