W for White Balance
This is a in-camera option, for setting the color tone correctly while shooting under varying light conditions. Generally, options like cloudy, direct sunlight, shade etc are available along with the Auto mode. The Auto mode suffices mainly, but be advised, during shooting HDR photos, or making a timelapse video, change it to some other setting other than Auto. This is because, in the Auto mode, the white balance might change between the subsequent shots, something that is not desirable while shooting in a series. For flexibility, I shoot in RAW format, and fix the issues in post processing.