Hound is a broad label for hunting dogs rather than a single breed. Scent hounds such as Beagles, Coonhounds and Foxhounds follow a trail with their noses, while sighthounds such as Greyhounds and Whippets chase what they see. Most dogs listed as hounds are scent-hound mixes with long ears, a short coat and a loud voice, so size and energy can range from beagle-sized to coonhound-sized.
Most hounds are friendly with people and other dogs, and they're happiest when following their noses. That instinct has trade-offs: many howl or bay, wander off after a scent, and treat training as a negotiation. A leash, a securely fenced yard and plenty of sniffing time matter more than the label, and a hound's size, energy and voice tell you more than its breed name.