A racquet string pattern is the number of mains and crosses on a tennis, badminton, squash or racquetball racquet. For example a pattern listed as 16/19 would mean 16 mains (the number of strings going up and down) and 19 crosses (horizontal strings or side to side).

Skipped and shared holes are terms used in stringing a racquet. When threading the mains you will usually skip the 7th and the 9th hole on either side of center at the head and throat of the racquet. These holes will then be used for cross strings. On some older frames and very few newer ones some holes will accommodate both main and cross strings. These are referred to as shared holes.

One piece and two piece are also stringers terms. Typically a racquet is strung using one continuous piece of string. Most string comes in a 40 foot piece or you can buy string on rolls coming in several hundred feet. The mains are threaded first followed by the cross strings. Certain conditions will warrant using two pieces of string. One piece for the mains and one for the crosses. Players who use hybrid sets (two separate and different types of string). Some racquet manufacturers require that two pieces be used even if it is the same string from a single package. Head and Prince racquets require two-piece stringing on most of their models if the crosses start at the throat or the warranty is invalid. They claim that one piece stringing adds undue stress to the frame.

Hope this helps answer all your questions!