what is their personality like?
Tempered aggressiveness that would provide the necessary drive to pursue and bolt the fox, without resulting in physical harm to the quarry and effectively ending the chase, which was considered unsporting.
Jack Russell Terrier
tempered aggressiveness that would provide the necessary drive to pursue and bolt the fox, without resulting in physical harm to the quarry and effectively ending the chase, which was considered unsporting. 
what's the lifespan of a jack russell terrier Thirteen to sixteen years what is it exactly? It is a small terrier that has its origins in fox hunting in England. how is it different from other related breeds? Their range of acceptable heights.
wiki:19561839
Jack Russell Terrier [SEP] Sporting parson
However, documented pedigrees earlier than 1862 have not been found. Several records remain of documented breeding by John Russell between the 1860s and 1880s. The Fox Terrier Club was formed in 1875 with Russell as one of the founder members; its breed standard was aspiration, and not a description of how the breed appeared then. By the start of the 20th century, the Fox terrier had altered more towards the modern breed, but in some parts of the country the old style of John Russell's terriers remained, and it is from those dogs that the modern Jack Russell type has descended.