Using the P mode (Program Mode)

I've been using a number of the user-controlled exposure modes.

Can some explain how they use the P mode?

On the D90 an asterisk appears next to the "P" when this mode is adjusted but, I haven't been able to identify the actual adjustment to the shutter and aperture the asterick represents.

Mode P is referred to as "flexible program" by Nikon. When the mode wheel is turned to P a P indicator with the asterisk above it appears in the control panel. It doesn't represent any particular change in in shutter speed or f/stop. Its just a reminder that the camera is set to shoot in that mode. In P mode the camera selects the optimum combination of shutter and f/stop for an average exposure. It's flexible in that you can change the combinations to meet your needs by turning the main command dial. All combinations of shutter speed and f/stop will produce the same average exposure. The mode is used in situations where all you need is average exposures, point and shoot type shots, but may need different shutter speeds for stop motion or a different f/stop to change the depth of field. Hope this helps.

Thank you, Joseph .... Yes your explanation of the "P" mode is very helpful.