In short: "remove the background" and "make it transparent" sound like the same request, but they're not — a flat color swap still leaves a solid box behind your subject, while real transparency is a per-pixel alpha channel that works on any background it's placed over. RemoveGifBG outputs real alpha, not a color-matched fill.
Most character animation — GIFs, video clips, exported art — is recorded or rendered against something: a white studio backdrop, a green screen, a solid app canvas color. That's fine as long as the asset stays where it was made. The moment you want to drop it onto a Discord chat, a stream overlay, a product thumbnail, or a different colored background, that flat backdrop stops being neutral and starts being a visible box around your character.
A proper background-removal pass does two separate jobs. First, it has to correctly decide which pixels are the character and which are background — including tricky cases like white fur on a white backdrop, or hair strands and fine detail at the edge of the subject. Second, it has to write that decision out as an actual alpha channel in a format that supports it, so "transparent" means transparent everywhere the file gets opened or embedded, not just in one app's preview.
Post-processing is the layer of work after that initial cutout: cleaning up edge fringe so no old-background color rings the character, fixing single frames where the model got the mask wrong so the animation doesn't flicker, and exporting at the exact canvas size and format a specific destination (a chat app, a stream overlay, a marketplace listing) actually requires. RemoveGifBG handles both parts — the per-frame cutout and the cleanup pass on top of it — automatically.
When you actually need transparency, not just a color swap