A display mode is a hardware setting that describes the dimensions and bit-depth of graphics that the display hardware sends to the monitor from the primary surface. Display modes are described by their defining characteristics: width, height, and bit-depth. For instance, most display adapters can display graphics 640 pixels wide and 480 pixels tall, where each pixel is 8 bits of data. In shorthand, this display mode could be called 640-by-480-by-8 (640x480x8). As the dimensions of a display mode get larger or as the bit-depth increases, more display memory is required.
There are two types of display modes: palettized and non-palettized. For palettized display modes, each pixel is a value representing an index into an associated palette. The bit depth of the display mode determines the number of colors that can be in the palette. For instance, in an 8-bit palettized display mode, each pixel is a value from 0 to 255. In such a display mode, the palette can contain 256 entries.
Non-palettized display modes, as their name states, do not use palettes. The bit depth of a non-palettized display mode indicates the total number of bits that are used to describe a pixel.
The primary surface and any surfaces in the primary flipping chain match the display mode's dimensions, bit depth and pixel format. For more information, see Pixel Formats.