Multimedia describes the ability of a computer to present and combine text, graphics, video, animation, and sound.

Before the personal computer boom, the word multimedia had a much simpler connotation – paper, glass, and acrylic on canvas was (and is) multimedia. The birth of the web led to a great potential for multimedia, because of the ability of networked computers to deliver this information to all users and to allow everyone to join in the world of multimedia publishing.

A bitmap is a mapped array of pixels that can be saved as a file.

Both JPEG and GIF are bitmap graphic formats. Currently, the only other way to store an image is as a vector graphic. You can’t easily scale bitmap images, but you can control every single pixel and thus achieve many effects impossible in vector graphics. Conversely, vector formats offer advantages of scalability and lower bandwidth requirements. When you compress a bitmapped image, you suck out some of the visual information.

To bypass this, the portable network graphics format (or PNG, pronounced “ping”) was designed to store a single bitmap image for transmittal over computer networks without losing this data.

Defined in 1992 by the Internet Engineering Task Force (IETF), multipurpose internet mail extensions, or MIME types, are a specification for formatting non-ASCII messages so that they can be sent over the internet.

When a browser comes across a file in an HTML document with a MIME extension (like .gif), the browser knows to display that file as an image. Many email clients also support MIME, enabling them to send and receive embedded media via the internet mail system.

Bit depth describes the file size of an image by orders of magnitude.

When wrangling with file size versus image quality, it’s often important to minimize the bit depth of an image while maximizing the number of colors. To calculate the maximum number of colors for an image of a particular bit depth, remember that the number of colors is equal to two to the power of what the bit depth is. For example, a GIF can support up to eight bits per pixel, and therefore can have as a many as 256 colors, since two to the power of eight equals 256.

The cell is nature’s building block, and the pixel is the web designer’s. Pixel is one of those half-baked half-acronyms:PICture ELement. It refers to how monitors divide the display screen into thousands or millions of individual dots. A pixel is one of those dots. An 8-bit color monitor can display 256 pixels, while a 24-bit color monitor can display more than 16 million. If you design a web graphic on a 24-bit monitor, there’s an excellent chance that many of your 16 million pixels won’t be seen by visitors to your site. Since the agreed-upon lowest common denominator palette for the web has 216 colors, you should design your graphics using 8-bit color. (see Bit Depth)

CMYK stands for cyan magenta yellow and blacK and is a color system used in the offset printing of full-color documents.

Offset uses cyan, magenta, yellow, and black inks and is often referred to as “four-color” printing. Monitors use red, green, and blue light instead, so they display images using a different color system called RGB. One of the great problems of the digital age has been matching colors between these two systems; i.e., taking a digital RGB image and making it look the same in print using CMYK. These problems are addressed by applications such as the Pantone Matching System.

To crop means to cut the pieces of an image that you don’t need.

Cropping differs from resizing because when you crop an image you retain the dimensions of the image. Resizing an image actually shrinks the image into smaller dimensions.

DeCSS is a software program that allows decryption of a CSS-encrypted movie and copying of the files to a hard disc (CSS stands for content scrambling system, and it’s used to protect the content of a DVD disc.) The DeCSS utility made online trading of DVD movies possible, although the interactive elements and outstanding audio/visual quality of DVD are compromised in the process.

Dots per inch (DPI) measures the resolution of images on a screen or printed page. The more dots, the better the resolution

Duotones are images that only display in two colors.

Like most visual techniques on the Web, duotones come from the world of print. In print, the more colors you use, the slower the production time and the higher the cost, so duotones were often an economical alternative. Duotones can also improve efficiency on the web by enabling the creation of cool-looking images with small file sizes. Duotones are made by first creating a grayscale image and then overlaying it with a different specified color.