It is a digital connection used to connect a graphics card to a screen.

It is advantageous (compared to VGA

VGA

This cable is used to connect a graphics card to an analog computer screen. The VGA connector consists of 15 pins arranged in three rows. This port is available in two generations : the original version and the DDC2 version, which allows automatic~type monitors.
Some laptops have a miniature version of this connector, the mini......

) on the screens where the pixels are physically separated.
The DVI connection so significantly improves the quality of the display to the VGA

VGA

This cable is used to connect a graphics card to an analog computer screen. The VGA connector consists of 15 pins arranged in three rows. This port is available in two generations : the original version and the DDC2 version, which allows automatic~type monitors.
Some laptops have a miniature version of this connector, the mini......

connection with :

- separation of shades of color for each pixel : perfectly clear picture.
- a digital (without loss) transmission of colors.

This is the equivalent digital analog RGB (red green blue) link but conveyed on three routes LVDS (low voltage differential signal) and by three shielded twisted pair.
In addition, as all (except CRT) screens are digital in-house, the DVI connection avoids analog-to-digital (A/D) conversion by the graphics card, and losses during transfer by the VGA

VGA

This cable is used to connect a graphics card to an analog computer screen. The VGA connector consists of 15 pins arranged in three rows. This port is available in two generations : the original version and the DDC2 version, which allows automatic~type monitors.
Some laptops have a miniature version of this connector, the mini......

.

Mid-January 2006 a European tax of 14 percent came knocking the monitors of 50cm (20 inches) and more, equipped with a plug DVI, manufactured outside of the eurozone.

There are three types of Sockets :

- DVI - A (DVI-Analog) which transmits only the analog signal.
- DVI - D (DVI-Digital) that transmits only the digital signal.
- DVI - I (DVI-Integrated) which transmits the digital signal to the DVI - D or DVI analog signal - A

Currently, most outputs DVI graphics cards are DVI - I.

It allows to keep the possibility to use a CRT screen, via an adapter \DVI to VGA

VGA

This cable is used to connect a graphics card to an analog computer screen. The VGA connector consists of 15 pins arranged in three rows. This port is available in two generations : the original version and the DDC2 version, which allows automatic~type monitors.
Some laptops have a miniature version of this connector, the mini......

.
In other words, although the majority of DVI connectors are the standard DVI - I, they will be used as the DVI - A if you have a screen CRT otherwise like DVI - D.