530 GlossaryGlossary
Web Design in a Nutshell, eMatter EditionFTP
File Transfer Protocol; a protocol for moving files over the Internet from one
computer to another. FTP is a client/server system: one machine must be
running an FTP server, the other an FTP client.
gamma
Refers to the overall brightness of a computer monitor’s display. In technical
terms, it is a numerical adjustment for the nonlinear relationship of voltage to
light intensity.
GIF
Graphic Interchange Format; common file format of web graphic images. GIF
is a palette-based, 8-bit format that compresses images with the lossless LZW
compression scheme. GIF is most appropriate for images with areas of flat
color and sharp contrast. See alsoLZW compression.
hexadecimal
A base-16 numbering system consisting of the characters 0, 1, 2, 3, 4, 5, 6, 7,
8, 9, A, B, C, D, E, and F. (where A through F represent the decimal values 10
through 15). It is used in HTML for specifying RGB color values.
HTML
Hypertext Markup Language; the format of web documents.
HTTP
Hypertext Transfer Protocol; the protocol that defines how web pages and
media are requested and transferred between servers and browsers.
imagemap
A single image that contains multiple hypertext links.
indexed color
In graphics, a system for rendering colors in 8-bit images. Indexed color files,
such as GIFs, contain an index (also called a palette or color lookup table) of
colors and associated index numbers, which is used to render color in the
image.
Java
A cross-platform, object-oriented programming language developed by Sun
Microsystems. It can be used to create whole applications; however, its
primary contribution to the Web has been in the form of Java applets, self-
contained, mini-executable programs.
JavaScript
A client-side scripting language developed by Netscape that adds interactivity
and conditional behavior to web pages. It has little in common with Java.
JPEG
A lossy compression algorithm developed by the Joint Photographic Experts
Group. It is used by files in the JFIF format, which are commonly referred to
as “JPEG files.” JPEG is most efficient at compressing images with gradations
in tone and no sharp edge contrasts. Photographic images are typically best
saved in JPEG format.