A Yorkshire Terrier has long, silky hair similar to human hair. Show Yorkies never have their hair cut, but for practical reasons many Yorkie owners find it best to have their dogs' coats cut. Yorkies are terriers, which means they are active and lively, and tend to get into mischief. Their fur very easily gets tangled, matted and full of foreign substances. Groomers offer a choice of several basic haircuts.
The Puppy Cut
The puppy cut is the most universally used hair cut for dogs of all breeds and it works well for Yorkies. Basically the body and leg hair is cut to an even length all over with clippers or scissors, but not completely shaved. The head and ears are trimmed with scissors to create a rounded look when viewed from the front. The hair under the tail may be trimmed shorter for hygienic reasons.
The Schnauzer Cut
The schnauzer cut is what groomers use to clip schnauzers. The back and body is clipped short, but the hair on the legs and tail is left long. The face is trimmed short on the top of the head but the beard is left long. It can be modified whatever way you prefer.
The Westie cut is normally used for the West Highland Terrier. The body is trimmed very short and can be shaved, but the head, eyebrows and beard are just trimmed a little and are left much longer than the body.
Designer cuts are "custom" cuts. This is where you can do some experimenting. Leave the ears long but cut everything else short; leave only the chest and legs long; cut the facial hair really short but leave the rest of the Yorkie long; cut the entire Yorkie except for her tail or leave a topknot for bows. The choice is yours.