Many different types of video adapters are available for PCs. Most conform to one of the video standards defined by IBM or VESA.

Each adapter offers several different video modes. The two basic categories of video modes are text and graphics. In text mode, a monitor can display only ASCII characters. In graphics mode, a monitor can display any bit-mapped image. Within the text and graphics modes, some monitors also offer a choice of resolutions. At lower resolutions a monitor can display more colors.

Modern video adapters contain memory, so that the computer's RAM is not used for storing displays. In addition, most adapters have their own graphics coprocessor for performing graphics calculations. These adapters are often called graphics accelerators.

Video adapters are also called video cards, video boards, video display boards, graphics cards and graphics adapters.

Also see Understanding Video and Graphics Adapters  in Webopedia's "Did You Know...?" section.

PC Guide's video card reference 
In-depth reference information for video cards. Looks at how the video card works in detail and includes sections on: video memory, interfaces, resolution and color modes, refresh, display standards, 3D computing, and performance issues.

Video Cards 
Describes the operation of the video card in general terms, and explains some basic concepts, including the main functions performed by the card. Also contains sections on interfaces, modes, memory, display standards, 3D video acceleration, full-motion video, and performance. This page is from "The PC Guide."

Video Display Standards 
Describes the different types of video standards including Monochrome Display Adapter (MDA), Hercules graphics card, Color Graphics Adapter (CGA), Enhanced Graphics Adapter (EGA), Video Graphics Adapter (VGA), and Super VGA (SVGA). This page is from "The PC Guide."

3D Video Acceleration
Describes some of the concepts involved in 3D video, as well as the issues related to the new 3D accelerators on the market. This page is from "The PC Guide."

PC Graphics Adapter Overview
Outlines the features and components of a modern PC video or graphics adapter. Includes graphics, diagrams and an integrated glossary. This page is from "The PC Technology Guide."

PC Mechanic's video cards page
Explains what a video card is and describes the different types of video standards.

Troubleshooting Video Cards
Lists some typical problems related to video cards. Most of the problems described relate to specific setup issues with the video subsystem. This page is from "The PC Guide."

Video Card Overview
Provides an overview of RAMDAC as well as information about unaccelerated and accelerated video cards, the video chipset, video BIOS, and video memory.

Video Card Performance
Describes some of the factors relevant to determining a video card's performance including bit width, video memory, system interface, benchmarking video cards, and the importance of drivers. This page is from "The PC Guide."

Video Modes, Resolution and Color
Describes the technical details of video modes and signals, as well as the major characteristics of the video image. This page is from "The PC Guide."