flat panel connections - technical definition

All newer desktop LCD monitors have two inputs: one VGA (analog) and one DVI (digital). If your computer has the traditional VGA port on the back, you have to cable it to the VGA input of your flat panel. In this case, the computer's display circuit converts digital signals to analog, and the monitor converts the analog back to digital, and there is a loss of sharpness in this double conversion. Since both the computer and flat panel are digital, keeping the signals in the digital domain produces the sharpest image, and there is a noticeable difference.

New PCs Often Have Only Analog Outputs
The problem is that many new PCs come only with an analog VGA connector for the monitor. However, there are countless third-party display adapters that support DVI and can be plugged into the PC.