Transparency really makes iLiteUp-YourLife! shine!  You may want to see both your off-light and your on-light together to create an interesting effect when your light is on. 

For Example, if you dont use any transparency, you can switch between your two beautiful children.  When both on-light and off-light are completely different pictures, leaving the pictures completely opaque makes sense. 

However, if you want the two pictures to blend together when your light is on, then you need to use the transparency sliders.  For example,  you can take two pictures that look great blended as your on and off light.

One other transparency effect that iLiteUp-YourLife! supports are pictures with an alpha channel already set.   Alpha channels allow an image to provide transparency on a per pixel basis.  You can do this to your pictures with many applications that can be run on your computer. 

These pictures will automatically blend without needing to set the slider.  If you do use the slider, then the transparencies will be changed, across every pixel, the more you move the slider.  You will get the best results and most flexibility with alpha channel based transparency in your original pictures. 

This option is specified right on the Light Selection view.