UU Game Terminology - Triggered
From Unstable Games Wiki
Effects are created by the successful resolution of an un-neigh'd card being played or generated from a card already in a Stable.
Some effects are only triggered by certain conditions. Triggered effects are always preceded by an "if" or "when."
Some triggered effects are mandatory (ex. "If this card is in your Stable at the beginning of your turn, DISCARD a card."), while others are optional ("If this card is in your Stable at the beginning of your turn, you may STEAL a Unicorn.").
Refer other Terms for more Information.