From M:TG Archive, a library of Magic: The Gathering information

The Internet has played an important role in competitive Magic: The Gathering. Strategy discussions and tournament reports frequently include a listing of the exact contents of a deck and descriptions of its performance against others. Known as "net decking", some players will take this information and construct a deck containing the same, or very similar, contents – relying on the expertise and experience of other players. While this strategy is often a good one, it is not a guarantee that the deck will repeat its earlier success. The player may be inexperienced, unfamiliar with the operation of the deck, or they may enter an event where a large number of other players have also "net decked". Many players advocate "Limited" formats of competitive Magic over "Constructed" formats because of this phenomenon.

[edit] Tournament archiving and Deck lists

• Magic the Gathering Stats Magic the Gathering online Tournament stats and deck archiving