Domestic Long Hair isn't a breed. It's the label for a mixed-ancestry cat with a medium-to-long coat, and the fur can run up to several inches, sometimes with a ruff, feathered tail or tufted ears. Colors and patterns cover everything from tabby and calico to solid black and smoke, and some cats resemble a Maine Coon or Persian without sharing that ancestry.
Because there's no standard, size and personality vary widely. Most adults weigh 8 to 12 pounds, though the fluff can make a cat look bigger. What they share is a coat that tangles without regular brushing and sheds moderately to heavily. Many live 12 to 18 years, so adopting one is a long commitment worth planning around.