The Russell Terrier is a predominantly white working terrier

Terrier

A terrier is a dog of any one of many breeds or landraces of terrier type, which are typically small, wiry, very active and fearless dogs. Terrier breeds vary greatly in size from just a couple of pounds to over 70 pounds and are usually categorized by size or function...

 with an insatiable instinct to hunt formidable quarry underground. The breed was derived from the Reverend John Russell's fox working terrier

Working terrier

A working terrier is a small type of dog which pursues its quarry into the earth. According to the Oxford English Dictionary, the name dates back to at least 1440, derived from early modern French terrier - from the medieval Latin terrarius from the Latin terra .With the growth of popularity of...

 strains that were used in the 19th century for fox hunting

Fox hunting

Fox hunting is an activity involving the tracking, chase, and sometimes killing of a fox, traditionally a red fox, by trained foxhounds or other scent hounds, and a group of followers led by a master of foxhounds, who follow the hounds on foot or on horseback.Fox hunting originated in its current...

. The Reverend's fox working strains were much smaller than the Show Fox Terrier and remained working terriers. The size of the Russell Terrier (10" to 12") combined with a small flexible, spannable chest makes it an ideal size to work efficiently underground.