When do I have to use 32-Bit color ( with alpha channel) and when 8-Bit (256 Colors) Icons?
32-Bit (with 8 bits alpha channel) files (PNG and ICO) are high quality files which allow full color, drop shadow, full brightness and transparency. We recommend using 32-Bit files in your applications in order to keep the full quality of the Icons, Those file types are supported in many development environments and Browsers. If your Application does not support those file types we recommend using 8-Bit (256 Colours).