Erase a white or flat background and get a transparent PNG. Whatever the automatic pass leaves behind, you clean up with the eraser.
There are broadly two ways to remove a background. One is to have a model recognise the subject and cut around it. The other is to work from colour. This tool does the second: it starts at the edges of the image and spreads inward through connected pixels of a similar colour.
That makes it clear which photos it suits and which it does not. A product shot on white, or an ID photo on a flat backdrop, is usually done in one pass. A portrait taken in a café is not — the automatic pass will struggle, and cleaning up with the eraser is faster than fighting it. It seems better to say that up front than to let you find out.
The result is always a PNG. JPG cannot store transparency, so saving as JPG would fill everything you just erased with white and undo the work. There is also no AI fill: whatever you remove stays empty rather than being invented back in.
Everything runs inside your browser. Because the image never reaches a server, we cannot store it or look at it. That difference matters when the file is company material or a personal photo.