It is possible that more pictures are ruined by camera shake than any other reason.
When a point-and-shoot picture is taken, the shutter stays open long enough to make a good exposure.
If there is not enough light, the shutter may remain open so long that the image is blurred by the movement of the camera in the photographer's hand.
Camera shake is caused by movement at slow shutter speeds
Problem: camera movement while shutter is open
Camera shake occurs while the shutter is open and exposing the film. If there is any movement, it will show up as motion lines and ghost images. This often happens in low light, with longer shutter speeds needed to expose the image.
out of focus
Many ruined photos are blamed on focus, when if fact the real culprit is usually camera shake. Here is how you can tell the difference: If you seeing ghost "doubles" on the image, you can be sure the problem is camera-shake.
Problem: Zooming makes camera-shake worse!
This is an important concept - The more you zoom in, the more the camera will shake. So getting a sharp picture with a zoom requires a much higher shutter speed than if you were using a wide-angle lens.
Solution: Faster shutter speeds
When shooting hand-held, the solution is to use faster shutter speeds. Photographers use the "one over the focal length" rule to figure out a safe shutter speed. Not a very catchy term is it? But it does generally work out. Here is a simplified version for everyday point-and-shoot cameras:
Traditionally, 35mm SLR Photographers used a simple formula - "one over the focal length". So if the lens is a wide angle 20mm, the closest safe shutter speed would be 1/15 to 1/30. If you know the 35mm SLR equivalent of your camera lens, you can use the following table:
Alternate Solution: Tripod
A tripod can be used to stablize the camera, allowing safe shutter speeds of a few seconds or more. Of course the problem is inconvenience.
Alternate Solution: Flash
If the camera fires its built-in flash, it will freeze subject motion. This generally works only if the subject is closer to the camera. Another drawback is mood - the flash will wipe out most of the subject's natural light.
Digital photographers, read about the Digital Push technique - a simple 2 step process to help avoid camera shake.