why transparent background turns white

it depends how you are saving it. If you have Photoshop Layers, and you remove or delete the background so that it is transparent --- it will stay transparent in the PSD file, but if you try to export to export it for the web you might see a WHITE background for GIF, PNG, and JPEG. JPEG does NOT do transparency, so if trying to save as a JPEG it jsut wont work, and you lose transparency. GIF and PNG however can save transparent files, you just have to make sure you cliek the "Transparency" checkbox in the save for Web Dialogue box (File>Export>Save for Web..).

Or if using File>Export>Export As -  you can save an image with transparent bsckground by selecting GIF, SVG, and PNG (for PNG again you need to select the "Transparency": checkbox.

hope this helps!

Cheers,
mark