There are many reasons for a dog lover to be familiar with the Labrador Retriever breed standard. As the most popular dog in North America and one of the most popular breeds in Europe, you can't avoid them. They are also popular for hybrid and designer dog breeds, but you can't get a good hybrid without good parent breed stock. You also might want to compare the dog you rescued to the Lab standard in order to know how best to raise your new dog.
A breed standard is a description of the perfect specimen of a particular breed, as agreed on by the reigning breed club. This breed standard is based on an ideal dog, not on any actual dog. No Lab can live up to all of the requirements of the breed standard. You can find a copy of the Labrador Retriever breed standard on any Labrador information website, book or even from good breeders.