Flash can be an important light source when shooting in low-light areas or unevenly lit situations. However, even if you only shoot photos at family gatherings with an inexpensive point-and-shoot camera, you've probably already come to realize the limitations of the flash as a primary light source. Countless photos with the foreground subjects "blown out" by excessive flash and overexposure litter hard drives everywhere, leading many photographers to try and work with as much ambient light as possible. All that said,your camera's flash doesn't have to be your enemy.
If you're stuck with your camera's built-in flash and no good way to increase lighting, there are a couple of tricks for preventing flash-induced "blow out." First, back away from the subject, zooming in slightly if necessary. Try taping some white tissue paper over the flash to diffuse and soften it. Many digital cameras allow you to reduce the flash intensity through the settings menu, so try that, too. If all else fails, just stick your finger over the flash. This is a hit-or-miss method, and the photo will be dark, but if you experiment, you might capture the ambiance you're looking for.
Of course, professional photographers can play a variety of tricks with flash, from using remote flash, bouncing the flash off a reflective surface, or using a flash in the middle of a long exposure to freeze the action. It's a very versatile lighting tool.