Do cards like Giant Growth create a one-shot or continuous effect?

Question

I'm curious as to how a card like Giant Growth works. I'm not sure if the effect on it is a one shot effect, a continuous effect, or something else.

If I had to guess, I think it works as follows: When Giant Growth (legally) resolves, a one shot effect is enacted. This one shot effect generates a continuous effect that lasts until end of turn and while the continuous effect lasts, the continuous effect gives the targeted creature gets +3/3.

Can one clarify as to whether or not I am correct, or if not, explain what really happens?

Answer 1

Not quite correct. It is just a simple continuous effect.

611.1. A continuous effect modifies characteristics of objects, modifies control of objects, or affects players or the rules of the game, for a fixed or indefinite period.

611.2. A continuous effect may be generated by the resolution of a spell or ability.

So Giant Grown resolving generates a continuous effect. No one-shot effect happens:

610.1. A one-shot effect does something just once and doesn’t have a duration. Examples include dealing damage, destruction a permanent, putting a token onto the battlefield, and moving an object from one zone to another.

"Getting +3/+3" is a continuous effect, not something that just happens at one moment in time. This can also be seen in the examples listed under the Continuous Effects section of the rules:

611.2c ... Example: An effect that reads "All white creatures get +1/+1 until end of turn"...

Answer 2

Effects don't create continuous effects.

611.2. A continuous effect may be generated by the resolution of a spell or ability.

Abilities create effects. Giant Growth has a spell ability that creates a continuous effect.

112.3a Spell abilities are abilities that are followed as instructions while an instant or sorcery spell is resolving. Any text on an instant or sorcery spell is a spell ability unless it’s an activated ability, a triggered ability, or a static ability that fits the criteria described in rule 112.6.

You seem to think "one-shot effect" means "spell ability", but that's not correct.

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So, does the spell have a one-shot effect or does it create a continuous effect? It definitely creates a continuous effect.

610.1. A one-shot effect does something just once and doesn’t have a duration. Examples include dealing damage, destroying a permanent, putting a token onto the battlefield, and moving an object from one zone to another.

611.1. A continuous effect modifies characteristics of objects, modifies control of objects, or affects players or the rules of the game, for a fixed or indefinite period.

(Emphasis mine.)