Discard
A Discard is the act of sending a card from your Hand, under normal circumstances, to the graveyard that can either be as a result of a card effect, or as a requirement to activate a card. Two such examples are "Spirit Reaper" and "Lightning Vortex". When a card is discarded it is not considered destroyed.
Discarding for cards like "Dark Core" or "Lightning Vortex" is considered a Cost. As such, "Dark World" monsters would not get their Special Summon effect.
A card being discarded does not necessarily go to the Graveyard. Although this is normally the case, cards like "Macro Cosmos" will send the cards to the Banished Zone instead; however, the card is still considered as being discarded.
