Jack Russell Terriers are among the most popular dogs in the UK, although the breed is not recognised by the UK Kennel Club. They are sometimes confused with a similar breed (which is Kennel Club registered), the Parson Russell Terrier.
Both are named after Reverend John Russell, a parson and hunting enthusiast who bred white and tan fox terriers. The Jack Russell has kept the distinctive white coat - in smooth and rough varieties, but always dense double coats - with black and tan markings.
Part of the Terrier group, Jack Russells have a reputation for being big dogs in a small body, since they need plenty of exercise and are generally bouncy and exuberant. As pets, it's worth exploring agility, obedience classes and other ways to challenge their energy and persistence.
'Jack Russell Terrier' is sometimes affectionately shortened to 'JRT'.