The Greyhound is a breed of dog, a sighthound which has been bred for coursing game and greyhound racing. Since the rise in large-scale adoption of retired racing Greyhounds, the breed has seen a resurgence in popularity as a family pet. It is also referred to as an English Greyhound.

According to Merriam-Webster, a Greyhound is "any of a breed of tall slender graceful smooth-coated dogs characterized by swiftness and keen sight", as well as "any of several related dogs," such as the Italian Greyhound.

It is a gentle and intelligent breed whose combination of long, powerful legs, deep chest, flexible spine and slim build allows it to reach average race speeds exceeding 64 kilometres per hour (40 mph).

The Greyhound can reach a full speed of 70 kilometres per hour (43 mph) within 30 metres (98 ft), or six strides from the boxes, traveling at almost 20 metres per second (66 ft/s) for the first 250 metres (820 ft) of a race.

Males are usually 71 to 76 centimetres (28 to 30 in) tall at the withers, and weigh on average 27 to 40 kilograms (60 to 88 lb). Females tend to be smaller, with shoulder heights ranging from 66 to 71 centimetres (26 to 28 in) and weights from 25 to 34 kilograms (55 to 75 lb), although weights can be above and below these average weights.

Greyhounds can be aloof and indifferent to strangers, but are affectionate with their own pack. They are generally docile, lazy, easy-going, and calm.

More Info: en.wikipedia.org