Discard
A discard is the act of sending a card from the 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," respectively. When a card is discarded it is not considered destroyed.
Discarding for cards like "Lightning Vortex" or "Raigeki Break" is considered paying a cost. As such, "Dark World" monsters would not get their Trigger effects. Discarding cards from hand during the End Phase due to Hand Size Limit will not trigger "Dark World" effects, as discarding at this time is not considered discarding as part of a card 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.
