Page "Digital Visual Interface" Paragraph 3

When a source and display are connected, the source first queries the display's capabilities by reading the monitor EDID block over an I²C link.

The EDID block contains the display's identification, color characteristics ( such as gamma level ), and table of supported video modes.

The table can designate a preferred mode or native resolution.

Each mode is a set of CRT timing values that define the duration and frequency of the horizontal / vertical sync, the positioning of the active display area, the horizontal resolution, vertical resolution, and refresh rate.