A hose bibb is an open ended, male threaded valve designed to accommodate a female hose connection. There are several variations of hose bibbs for sale with varying dimensions, materials, safety devices and sizes. Below are images of some different types of hose bibbs.
Sediment faucet hose bibb
Common hose bibb that offers no added protection. Can be found with a variety of valve types and body shapes.
Frost Free Hydrant
Self draining to prevent freezing and includes integrated vacuum breaker. 
Boiler drain hose bibb
Used for and residential commercial hydronic heating systems. 
Tamper proof commercial hydrant
Key operated frost free hydrant with built in vacuum breaker. 