The Jack Russell Terrier is a small, compact, athletic dog that resembles a Fox Terrier. These dogs are white (at least 51%of them) with reddish black, tan, or brown markings, particularly in the head and tail. The dog's nose is always black and its almond-shaped eyes are dark brown. The ears are v-shaped and fold forward.
The Jack Russell features a flexible body and a rather small chest that allows him to get low to the ground while going after his prey. The dog carries his docked tail gaily and it is set rather high on the body. The coat is generally rough but is also smooth in some spots. It has long body hair, a bit of a fuzzy face, and a smooth head. An Irish-type called the Jack Russell Shorty has shorter legs than the English-type.
The Jack Russell is a very devoted and loving dog, and is also rather perky and happy most of the time. The Russell is spirited and obedient, but at the same time, absolutely fearless. However, he can be cautious. His amusing nature makes him content to play with toys for hours on end. He enjoys games too. The dog is friendly and kind to children, especially those who don't tease or beat him.
Intelligent, willful and determined, 
the Jack Russell can be difficult to train, and an experienced trainer is often needed to discipline him. This dog can be aggressive with other dogs if not properly trained. Some Jack Russell's have even been killed in dogfights. If you don't want this to happen to your dog, get him to socialize in the early months. This can help eliminate this belligerent trait. Also, this Terrier has stronger hunting instincts than most other Terriers, so you should not trust it alone with other small animals.
Jack Russell's like to chase things and explore, so do not let them off the leash unless you have trained the dog well. They also like to dig and bark and can get restless and destructive if restricted and not allowed proper exercise. They are experts at climbing and jumping, and can clear a fence five feet high. This is a big dog in a little dog's body, so this breed is not for an inexperienced dog owner. Remember that you need to be as strong-willed as your dog, or the dog will take over your life!
The Jack Russell Terrier can do fine in an apartment if you give it enough exercise. The dog tends to get destructive if it does not have enough to do. If you have an apartment, a dog crate is recommended for the times when you are not home. This will also prevent the dog from urinating or defecating in the house, as most dogs will not soil the place where they sleep unless absolutely necessary. When you get home, be ready to get your Jack Russell to exercise, unless you want to be annoyed all evening with requests for belly rubs and tug of war games!
