Cool Tech - Back Lighting

I was on stage at my church on Wednesday night. I noticed that we have lights positioned just in front of fabric sheets at the back of the stage. The lights, which are made up of probably 50 to 100 bulbs, change colors and light up the fabric panels behind them. It really cool to watch the effect. I'm going to talk with our technicians to get some more details, but just watching the lights work produces an always changing, almost never ending background on stage. It's pretty cool to watch!