Flash

Flash has it's pros and cons. The good thing about using flash is that it makes sure the photo doesn't come out blurry. Flash has a way of "freezing time" which captures the moment you want, not whatever comes out. Flash also makes the picture bright and visible. The cons of flash is that it could drain the picture of the natural light. Anything that makes light disapears because the flash of the camera cancels it out, so to speak.
Flash is good to use when your outside but there's still shadows. Or when your at a sporting event. The players are moving quick and with flash you catch them without the blur. Flash wouldnt be good at a birthday party when they're blowing out the candles or during a light show for example.
The picture I used is better without flash because the flash would have taken away the lights in the background. The lights make the picture such an interesting portrait of the DJ.