@Corne2Plum3 They were asking what software people use to create animations.
@Quickstarter I think everyone has their own preferred software. Like there isn't one that's specifically best for osu. They all kind of do the same thing. That being said, Adobe Animate is pretty new and looks really easy to use. Basically photoshop with the ability to animate layers.
Me personally, I just use photoshop and move my elements frame by frame and save each frame as I go along. For example, on my personal skin, I made the back button have a pulsing blow to it that fades in and out. I basically just kept duplicating the "glow" layer and adding 5% gaussian blur, saving it as a new frame and repeating that process until I had 60 frames.