Domestic Long Hair isn't a breed. It's the label used for a mixed-ancestry cat with a long coat, the fluffy counterpart of the Domestic Short Hair. These cats come from the general cat population, so they appear in every color and pattern, from tabby and calico to solid black, smoke and bicolor. Some look a lot like a Maine Coon or Persian without sharing that ancestry.
With no breed standard, size, coat texture and personality vary from cat to cat, and adults commonly weigh 8 to 15 pounds. What they share is a coat that needs regular brushing to prevent mats and hairballs, plus the broad genetic diversity that tends to keep mixed cats healthy. That makes them a good match for indoor homes where a brush is part of the routine, and meeting a cat in person will tell you more than the label.