EX Emerald is the name given to an Expansion of cards and Theme Decks for the Pokémon Trading Card Game released only in English and European languages. It is notable for being composed of several Japanese sub-sets, as opposed to a Japanese expansion.
EX Emerald was conceived to tie in with the release of Pokémon Emerald, a trend Nintendo have followed since their occupation of the TCG. Since no Japanese set correlated with this, Nintendo used cards from other sources.
The set contains all of the cards found in the Japanese Quick Construction Packs and the Japanese Emerald Gift Set. In addition, several Japanese Promotional cards were included, as well as a few cards which were first released in English. All of these cards have since been released in Japan; many as Promotional cards, the rest in Eidolon Forest.
Since only the Pokémon-ex in the Quick Construction Packs were created with competitive play in mind, very few cards from EX Emerald see much use by players.
Before the release of this set, the Japanese producers of the TCG requested a list of popular cards from English players. Pidgeot, Dark Dragonite, Dark Tyranitar and Dark Ampharos were frequently mentioned, leading to belief this was the inspiration behind the production of the Trainer Card Battle Frontier, which restricts these cards' abilities.
EX Emerald was the first set to be released after the Pokémon TCG website  had introduced a new card spoilers feature as a tournament resource. However the file containing information on all the new set was uploaded before the Prereleases, and was discovered and distributed over the internet. The file was then taken down, but not before the data had been copied onto several major fan-sites. Since this incident, new card spoilers are only uploaded after the set is commercially released.
This is the only EX Series set not to have Pokémon after their debut.
This was the first English set to contain holographic Basic Energy cards (popularly called Matrix Energy cards because of their design), which replaced the reverse-holographic card in every third pack.
The reverse-holographic design for this set features a foil Poké Ball pattern with stars and the EX Emerald set logo.