Does a mana ability go on the stack and can it be responded to?

Mana abilities are a special category of abilities that bypass the normal stack process entirely. Under CR 605.3a and 605.3b, activated mana abilities are activated without using the stack, and triggered mana abilities (those that trigger from mana abilities) also don't use the stack. This means no player receives priority between the activation and the resolution of a mana ability.

An ability qualifies as a mana ability if it meets all of CR 605.1's criteria: it is an activated or triggered ability, it could produce mana as part of its effect, and it does not have a target. If any of those conditions aren't met — for example, if the ability targets something — it becomes a regular ability that does go on the stack and can be responded to.

Because mana abilities resolve immediately, players cannot respond with spells or other abilities between the activation and its resolution. This is what makes tapping lands for mana so smooth — your opponent cannot counter your Forest's tap ability or destroy the Forest in response to you generating the mana (though they could destroy it before you activate it).

Concrete example: You tap a Llanowar Elves to add one green mana. This is a mana ability (CR 605.1), so it resolves immediately without going on the stack. Your opponent cannot cast Lightning Bolt to destroy the Elves and prevent the mana from being produced — the mana is already in your mana pool.

Note: Abilities that happen to produce mana but also have a target (like some older cards) are not mana abilities and do use the stack normally per CR 605.1b. Always check all three criteria before assuming an ability is a mana ability.