Dogs (Canis lupus familiaris) are the most common pet in the world and have been domesticated for thousands of years. They are descendants of wolves and share many characteristics with them, including a strong sense of smell, high intelligence, and a pack mentality. Dogs come in a wide variety of shapes and sizes, and can be trained to perform a number of tasks.
Dogs have long been used as working animals, helping humans with hunting, herding, protection, and even disability assistance. In recent years they have also become popular pets, and their popularity is reflected in the vast amount of research that has been done on them. Dogs are now known to be capable of understanding up to 250 words, and they are able to reading human emotional states by interpreting facial expressions.
The bond between humans and dogs is one of the strongest known between any two species, and dogs have been shown to provide numerous health benefits to their owners. For example, dog owners tend to have lower blood pressure and cholesterol levels, and are less likely to develop cardiovascular disease. Additionally, dogs can help reduce stress and anxiety, provide companionship, and increase opportunities for physical activity.