Counterfeit

A counterfeit card is a fake trading card. Most counterfeit cards in the context of Yu-Gi-Oh! are of OCG or TCG cards, or are made to mimic them. Counterfeit cards are usually made with the express purpose of selling them as real cards to make a profit, which distinguishes them from fan-created cards, which may be sold as art but not as real cards.

Many counterfeit cards can be easily recognized by such things as oddly colored or low-quality card backings or images, or very poor grammar in card names, effects, and other card text, which may use the wrong font or be incorrectly sized. Counterfeit Spell and Trap Cards may have ATK and DEF values and maybe even Level stars printed on them, and some cards may have their rarity printed following their effect or description due to copy-pasting description of websites that usually write the rarity after the effect. A few of the fake cards even have the words "effect unconfirmed", making the copy-pasting more obvious.

Fake trading cards are often sold in markets, non-legit stores, auctions, and online.

Fake booster packs/boxes
Most fake boosters and boxes have the following tell-tale signs:
 * Incorrect format, such as Levels/Ranks or ATK/DEF on what is supposed to be a Spell/Trap card.
 * Reversed Konami logo or incorrect spelling of "Konami" (e.g. Konaini) or no Konami logo at all.
 * Incorrect fonts.
 * The use of profanity or improper grammar.
 * Wrong card name, effect, Level, border, artwork, or stats.
 * The use of OCG names or artworks in what supposedly is a TCG card.
 * Attributes without kanji, or nonexistent Attributes such as Sound, Devil, God or Land.
 * Incorrect ordering of card type. Normally, the Monster's Type is listed first, followed by any subtypes, e.g. "Machine/Effect", "Warrior/Synchro/Effect", or "Dragon/Spirit".
 * Very brightly or incorrectly colored artworks, backs, levels/ranks or borders.
 * Bad picture quality (Duel Terminal cards are often blurred because of their parallel coating and are much darker than other cards; as such, their artworks should not be confused with this).
 * Diagonal Secret Rare-esque lines printed in black onto a non-holofoil artwork.
 * Common mistakes with the Type include: "Machine" written as "Maching", "Warrior" as "Fighter", "Zombie" as "Undeat", "Fiend" as "Insect", "Dinosaur" as "Dragon", and "Angel" as "Fairy".
 * Card types which feature the type and sub-type being separated by a period rather than a slash (e.g. "Fighter.Effect").
 * Fusion Monsters which list "Melting", "Amalgamation", "Mix" or "Combination" rather than "Fusion" in the type. Likewise, Ritual Monsters which list "Ceremony" instead of "Ritual". Synchro Monsters are often called "Homogenity" also the Tuner monsters are called "Adjuster".
 * Incorrect terminology in card descriptions (e.g. using "Adversary"/"Rival" instead of "Opponent", "Life score" instead of "Life Points", "fieldside positioned" instead of "face-up", "Common Monster" instead of "Normal Monster" and "bout" instead of "Phase").
 * Card Number/Limitation Text missing from the lower left corner. However, do note that there are some real cards, such as "Labyrinth Wall", which do not have a Card Number.
 * Copyright text (&copy;1996 KAZUKI TAKAHASHI) missing from the lower right corner next to the Eye of Anubis.
 * "Kazuki Takahashi" spelled incorrectly due to reading the kanji incorrectly (高橋 和希).
 * On boosters, the seals at the top and bottom should be vertical, not horizontal.
 * Too reflective, or spiral/circular reflective patterns over the entire card.
 * No "English Edition" sign on top of the booster.
 * No Eye of Anubis, or the Eye of Anubis is not reflective (though OCG cards with the original layout all lacked the Eye of Anubis). Also, it should never be able to peel off the hologram, if it is a sticker, the card is fake.
 * Incorrect Rarity (most fake cards have Common as the only Rarity) or Rarity that is not holographic (e.g. a card has gold letters that are not reflective).
 * Strange logo, as in "New Yu-Gi-Oh!" or both "Yu-Gi-Oh! GX" AND "Yu-Gi-Oh! 5D's" logo in one pack/box/tin.
 * On boxes, the Cover Card does not match the set, or the set name given does not match any officially released set. Additionally, on boosters, the monster featured on the cover may not be the correct one (for example, "Dragorado" on the cover of a "Galactic Overlord" booster).
 * Starter Deck that purely focus on 1 specific archetype, even going as far as printing anime-only cards that are related to the archetype and put it into the Starter Deck. Note that official Starter Decks sometimes have cards related to an archetype in them, but they never purely focus on it.
 * On a character's Starter or Structure Deck, the featured cover card is not related to the character (e.g. "Cloudian - Eye of the Typhoon" as cover card for a supposedly Jaden-based Deck).
 * Decks in tins (note that there ARE real Yu-Gi-Oh! tins, but they are much bigger than the fake "deck tins", and always shows the cover card that match the tin. The real tins also contain only booster packs, not full decks).
 * Counterfeit cards sometimes feel waxy or have a thin layer of plastic over the card's surface.
 * 1st Edition cards that don't have a gold hologram in the bottom right are fakes.
 * Lack of the "Yu-Gi-Oh! Trading Card Game" logo on the card's backing (the Egyptian God Cards are the only exception; they have no logos on the back and have red, yellow, or blue-tinted backing designs. On that note, fake God Cards may have the normal coloring and logos on the back that all the normal cards have).
 * Cards that claim to be Exodia in a single card (except "Exodia Necross" or "Exodius the Ultimate Forbidden Lord").
 * Some starter decks have a Yu-Gi-Oh logo that say Shonen Nump (shown at Australia).