When you are leaving your photos in to be printed, you may choose the option Fill-in or Fit-in. Fill-In is the standard, default setting.
Fill-In Explained
Most compact cameras and phones take photos in a 4:3 ratio. What this means is that if you select a 6×4 size print (a 3:2 ratio), the whole sheet will be filled, but this will result in parts of your image being cropped.
Fit-In Explained
If cropping the image does not suit you, as you need the whole image printed, you may choose to print as Fit-In
Alternatively, if neither of these options suits you, you will need to crop your image to be a 6×4.
If any further explanation is required, Please do not hesitate to contact us.