Mastiffs are part of a larger group of dogs, called Molossers, which includes Great Danes, Bullmastiffs and Rottweilers. This is an ancient group of dogs, and the English Mastiff is the modern breed most commonly called the generic term Mastiff.
The English Mastiff can reach up to 30 inches tall and weigh up to 190 pounds. This breed is stocky and features heavy bones and strong muscles. Mastiffs live around 10 years and have numerous health concerns, but their short coats require little grooming. Despite their large size, Mastiffs prefer to stay indoors because they don't like heat and enjoy playing the role of protector or guardian, which is a role they have filled since ancient times. These are low-energy dogs that are shy around strangers but friendly toward animals and affectionate toward owners.
Other breeds of the Mastiff group include the Tibetan Mastiff, American Mastiff and Neapolitan Mastiff. These breeds are similar to the English Mastiff but have minor differences that set them apart, such as small variations in size and appearance. The American Mastiff, for example, can be as tall as 36 inches and weigh up to 200 pounds. American Mastiffs also have a less droopy face than the English Mastiff.