In case you don't have any idea what a magnetic selection tool is, let me give you a simple explanation. As you drag around an image with your mouse in order to trace around it, a magnetic tool like smart scissors, finds the edges of the image and locks to them. As long as there is good color contrast between the image and the background areas, a magnetic tool neatly selects the image. If the tool doesn't give you the desired selection area, you can adjust it so it grabs exactly what you want to cut out. This is true with Photoshop's magnetic lasso and Fotoflexer's smart scissors.
I'm often asked by colleagues how to remove the background from an image; how to "cut out" the subject of the photo. Most of the time I just cut it out for them because it's just easier and less time-consuming than teaching them. But now I will refer them to FotoFlexer.
I've searched the web for online background removal tools. Most are mentioned in my post Three free alternatives to the no-longer-free Clipping Magic (05/22/2014). None of them is as good as smart scissors which, rather than removing the background, selects an object to be cut from the background. In the post I mention Fotoflexer's smart cutout, which is a feeble attempt at duplicating Clipping Magic's excellent background removal process. Forget smart cutout; go with smart scissors instead. All other background removal sites I've found can't even compare with Clipping Magic, but if you want to pluck an image from its background, use the free Fotoflexer smart scissors.
Just upload your image to Fotoflexer and click the GEEK tab at the far right. Then choose Smart Scissors. See my video for instructions on selecting, adjusting the selection, and cutting the image out to create a png file with a transparent background.