are mana abilities in magic the gathering abilities that cost mana to activate?

[kartiv]

what is a mana ability is it an ability that has mana in its cost

like is Nightwing Shade a mana ability and therefore cannot be countered with Voidslime?

[kip]

mana abilities are only those that produce mana

like for example

birds of paradise

[Arix]

Plus a few other rules. An activated mana ability is a mana ability that could produce mana, doesn't have any targets, and isn't a loyalty ability. A triggered mana ability is a triggered ability that could produce mana, doesn't have any targets, and triggers off another mana ability.