Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keyword abilities (such as equip and unearth) are activated abilities and will have colons in their reminder text.

Triggered abilities use the word "when," "whenever," or "at." They're often written as "[Trigger condition], [effect]."

Turn-based actions and special actions like the normal card draw, combat damage, or turning a face-down creature face up can't be targeted. Mana abilities also can't be targeted.

The last mode can target delayed triggered abilities. Notably, it can target the delayed triggered ability that exiles an unearthed permanent at the beginning of the next end step. If that delayed triggered ability is countered, the unearthed permanent remains on the battlefield indefinitely. It will still be exiled, however, if it would die or otherwise leave the battlefield for any other reason.