One commonly heard phrase that resounds around the internet is "If you shoot in auto mode you're letting the camera make all the choices for you". This bit of photographic fallacy has been passed down from "pros" to amateurs and continues to be spread around everyday.
I'm here to bust that myth and set the record straight. Anybody that insists that you must shoot everything manual is a fool! Programmed Auto (P) is a very cool mode that picks the settings based on lighting conditions as well as how the light is distributed around the scene. Using a database of over 30,000 images the metering system predicts what kind of photo you're taking and and chooses the settings accordingly.
The great part about the Programmed Auto or P mode is that you can adjust the shutter speed or aperture at any time by rotating the main command dial. This is called Flexible Program. Dial to the right to open the aperture/increase the shutter speed and to the left to close down the aperture/slow down the shutter.
In addition you can turn on Auto-ISO and set a minimum shutter speed if you're concerned about maintaining a certain shutter speed to freeze action.
In effect, P mode is automatic, but YOU still control the settings. The camera just offers a basic exposure guideline which you can override at any time.
Using P mode can really speed up your picture taking process while still allowing you quite a bit of control over your exposure settings.
(pssst,I often use Programmed Auto when shooting concert assignments, don't tell anyone!)