What does the hold keyframe do?

[Ar_D]

I was trying to make a tutorial with one of my old ideas, and I thought that the box shape keyframe might be used to give a sudden change to the parameter, unlike the normal ones. But it works same as the other.

Is there a way to create a sudden change in the parameter, without creating 2 keyframes? And also what does the hold keyframe does?

[shotcut]

Hold = hold/keep/sustain the current value until the next keyframe (assuming it changes the value) instead of interpolating

[Ar_D]

Thanks, I thought adding the hold frame after the normal interpolate ones also does that. But it didn’t do, now I understand.

[TimLau]

Here is a visual example