The modern day Jack Russell Terrier traces its origins back to the early 19th Century, to a dog name Trump, whom was purchased by the Reverend John Russell. The Reverend John Russell, from whom the Jack Russell Terrier takes its name and were first bred by, can trace their origins back to the now extinct English White Terrier.
The Reverend John Russell bred and developed the breed primarily for fox hunting. Because of their muscular and sturdy build, the Jack Russell Terrier was the perfect hunting companion, able to actually go back into the den and ferret the foxes out.
Jack Russells are similar to the modern day breed of Fox Terriers, with whom they are commonly confused with, as well as the Parsons Russell Terrier and the Russell Terrier. Unlike the aforementioned Parsons and Russell Terrier, the Jack Russell Terrier is not a breed currently recognized by the AKC.
The Jack Russell terrier is a very exhuberant and active breed, that needs frequent stimulation and a high level of exercise. It is because of this exuberance and stamina that they are the perfect companions on fox hunts, as they can rustle the prey out of its den, without causing any bodily harm to themselves or the prey.
Although the lineage of the modern day Jack Russell Terrier dates back to the early 19th Century, after World War II their role of hunting companion turned to that of family pets. It was at this time that they were commonly cross bred with Welsh Corgi's, Chihuahua's and other small breeds of terrier. These combinations were commonly referred to as "Puddin Dogs", "Shortie Jacks" or "Russell Terriers".
In the late 1990's the AKC considered acknowledging the breed of the Jack Russell Terrier officially, but the JRTCA (Jack Russell Terrier Club of America) didn't want the acknowledgement made official. After altering the previous standards for consideration, the AKC accepted the breed in 2001, but as the Parson Russell Terrier. The modern day version of the Jack Russell Terrier is still not recognized by the AKC.
Due to the working nature of the breed, the Jack Russell Terrier has remained very much the same for 200 years--exuburent, vibrant, and energetic. Because they are so alert and always attentive, they make wonderful breeds for training. They are featured in many TV shows, ads, and Movies. Wishbone, the RCA Victrola dog, and Eddie (from Frasier) are a few of the more well known Jack Russell's.
The typical Jack Russell Terrier can live a long, healthy life, with the average life span being 13-16 years. For a list of health conditions that tend to afflict the Jack Russell Terrier, note the previous post Health Conditions to Look for in your Jack Russell Terrier