Remove BG uses an image segmentation model based on BiRefNet, running on Cloudflare's global network. The model looks at the whole picture to decide what the main subject is, then traces its outline pixel by pixel.
Instead of a hard yes-or-no mask, the model produces an alpha matte: every pixel gets its own transparency value. That is why strands of hair, fur and soft shadows blend into a new background instead of showing a jagged edge.
Because the model runs on servers close to you, a typical background removal is finished in two to four seconds. Your image stays in memory only while it is processed and is never written to storage.
Cutting out hair by hand with a pen tool or a selection brush can take a skilled editor a long time. Remove BG does the same job in seconds, so you only spend time on the parts of the design that matter.