|Japanese (base text)||
Face-down cards have no properties (name, Attribute, Type, Level/Rank, ATK, DEF, effect) until they are changed to face-up. A face-down card being looked at or revealed is still considered face-down (although its properties can be determined by card effects while being revealed) and is returned to its original position once the player(s) have finished viewing it.
In Yu-Gi-Oh! ARC-V, small orbs with glowing red eyes appear on top of face-down monsters.
In the Decks
Face-down cards in the Extra Deck can be looked at by their possessor at any time, but cannot be looked at by their opponent.
Summoning a Pendulum Monster from Extra Deck
On the field
During a game, cards are normally placed face-down by Setting them. Face-down cards on the field can be looked at by their controller at any time, but cannot be looked at by their opponent, unless stated otherwise.
Face-down cards on the field can be flipped face-up. (Flip Summon for monster and Activation for Spell/Trap cards, in general cases) However, face-up cards cannot be Flipped face-down, unless an effect specifically states so.
Monster Cards can be placed on the field in face-down Defense Position, generally by Normal Set (it is not possible for monsters to be in face-down Attack Position, post errata of "Darkness Approaches"). Some effects may Special Summon face-down, but only if a card state explicitly it can do so.
Link Monsters cannot be placed face-down.
Spell and Trap Cards can be Set in the Spell & Trap Zones or the Field Zone (in the case of Field Spell Cards). Quick-Play Spell Cards and Trap Cards cannot be activated during the turn they are Set. Pendulum Monsters cannot be played face-down in Pendulum Zones.
Info on cards affected by Flipping face-down
When a card stops being face-up, in this case, because of being flipped face-down, it will lose some specific information/applications on it.
- Whether if it was placed on the field by specific method or not (Special Summoned by certain effect, Tributing a certain monster for Tribute Summon, etc).
- Any previously applied effects.
- Its place before being summoned/placed on the field.
Info not lost
- Material used for its Summon.
- Its time of Summon.
Some card effects can banish cards face-down. Cards that are banished face-down can be looked at by their possessor at any time, but cannot be looked at by their opponent. However, the number of banished cards (including face-down banished cards) is public knowledge.