A.3 - Glossary

A proprietary system developed by Microsoft for use with their Internet Explorer Web browser (and subsequently, other Web-enabled applications) to extend the capabilities of the browser, in particular, to add interactive elements or to display graphic files in a format not covered by the core W3C standards. It is analogous to the plug-in architecture developed to extend Netscape’s Web browser (see Browser Plug-in).

Apache Web Server

Apache is the most common Web server employed on the Internet. Apache is an open source Web server first developed for UNIX platforms. It has since been ported to LINUX, Windows NT/2000 and Macintosh, and, in most cases, is distributed and maintained free of charge. Over 50 percent of Web sites use Apache; almost double its nearest competitor, Internet Information Server (see Internet Information Server ) from Microsoft.

ASCII

American Standard Code for Information Interchange (ASCII) is a set of characters (letters, symbols, spaces, numbers and punctuation) used on most present day computers. ASCII files (also called “Plain Text”) are saved without any formatting, and can be opened by virtually any computer program. Most applications save data in a proprietary binary format (see below) because binary files are more compact. HTML is an example of a text file format (often an extension of ASCII called Latin-1). See A.1–What is HTML

Binary File Format

“Any file format for digital data encoded as a sequence of bits but not consisting of a sequence of printable characters [ASCII] (text). The term is often used for executable machine code.

Of course all digital data, including characters, is actually binary data … but the distinction between binary and text is well established.” [1]

Binary files are a sequence of bits and bytes that only a computer can read. Often, the binary format of one application is not readable by another application. Microsoft Word files, for instance, need to be manipulated with the Microsoft Word application to be of any use.

Browser Plug-in

A plug-in is a software module that is installed to extend the functionality of a Web browser. Usually, a plug-in is necessary to publish information in a format other than a core standard. Originally developed for the Netscape browser, plug-ins can also be installed and used in versions of Internet Explorer up to version 5.5. Versions of Internet Explorer higher than 5.5 do not support the Netscape plug-in and can only be extended using Microsoft’s Active-X system (see also Active-X).

Cascading Style Sheets (CSS)

Style sheets are used to describe how documents are presented on screen, in print or perhaps even pronounced.[2] Style sheets are used in a number of applications. Word processing programs such as Microsoft Word and Word Perfect and Desktop Publishing programs such as Adobe PageMaker or Quark Xpress use style sheets to organize layouts. Styles sheets allow a designer to set a style for an element of a layout once and have it apply to all other elements in the document. For instance, a style sheet could specify that all paragraphs in a document be rendered at 12-point type with the font Helvetica, and all headings be rendered at 14 point with the font Arial. These rules would apply throughout the document automatically without having to select each paragraph and apply the type style each time.

HTML uses a similar technique to describe on-line layout. The specification is termed “Cascading” because the styles are applied from the top down (or think if it as from the outside in). To illustrate, a style declaration for paragraphs is written as:

This declaration will render all paragraph font tags with the Arial font at 10 points (see A.1 – What is HTML?) and all tags for bold text () with the font impact and the color blue. Now, a paragraph in an HTML file can be written:

The tags are contained entirely within the tags, the style sheet declaration of the section marked with the tags will override the style sheet declarations of the tags. The bold text will be in a different font and color. Notice that since there was no font-size declaration, the text will all be the same size.

CSS is important in HTML design because it allows HTML to separate structure and layout, making HTML documents more portable. For instance, you could write one article and allow users to choose which style sheet to apply. One style sheet could be for Netscape browsers and one for Internet explorer, for instance; or one for users who prefer larger type. Instead of having to publish two or three HTML documents, it would be easier to publish one and three small style sheets.

The New York Public Library system has an excellent on-line style guide, with links to numerous resources. It is worth investigating at http://www.nypl.org/styleguide/.

Extranet

A term for an intranet or part of an intranet extended to include users from outside of the hosting organization (see also Intranet), generally to facilitate collaboration.

Frames

Frames are a way to split a browser window up, and load one or more HTML pages into the same browser window. If used correctly, frames can help organize a Web site. However, they have some disadvantages, and should be used sparingly.

Figure 1 (opens in a new window) shows a simple example. Figure 2 (opens in a new window) illustrates some of the pitfalls.

File Transfer Protocol (FTP)

FTP is a protocol for exchanging files of all types over the Internet. It is a sub-protocol of the TCP/IP protocol suite.

Hyperlink

A segment of text or a graphical item that serves as a cross-reference between parts of a hypertext document or between files or hypertext documents. Also called hotlink. [3]

Hyperlinks are the heart of the Internet. It allows one document to “point to” information in another section of the document, or another document entirely.

HyperText Transfer Protocol ( HTTP )

A sub-protocol of the TCP/IP suite (also called the TCP/IP “stack”), HTTP is used to move HyperText files on the Internet from server to client. It is the underlying protocol of the World Wide Web, and defines how Web servers and Web browsers should transmit and receive information.

Intranet

A network internal to an organization or enterprise that relies on Internet protocols for file sharing. Intranets are Web sites intended for a specific audience, usually the employees of one company. This internal communications tool is becoming more and more popular, for the same reasons that publishing a Web site have made it the fast-growing medium that it is. Information such as company memos, employee handbooks, schedules, important dates, company newsletters, etc., can be published on an internal Web site, and cost savings in printing and duplication, staff time and increased distribution of information to employees who are offsite make an intranet a powerful tool.

Internet

A worldwide system of interconnected computers sharing information through a common networking protocol (currently TCP/IP). HTTP, FTP, GOPHER and SMTP are examples of protocols that are delivered over this network.

Internet Information Server (IIS)

IIS is the Web server developed by Microsoft, and distributed as part of the NT/Windows 2000 Server package. It is currently second in popularity to the Apache Server (see Apache Web Server above). [4] IIS has not been ported to any other platform outside of the Windows family of operating systems.

Internet Explorer

Internet Explorer is a Web browser developed by Microsoft. Currently the majority of computers have a version of Internet Explorer installed, although Netscape has a strong minority share. Internet Explorer is installed on perhaps as many as 75 percent of the PCs in use today. Since many users have both browsers installed, there is no clear way to tell how many users prefer Netscape or Internet Explorer. With two strong market shares, Web sites must be able to be displayed by both major browsers in order to be considered effective.

Internet Protocol (IP)

The Internet protocol defines a method to assign a unique address to every device (router, modem, computer network card, hub, etc.) that connects to the Internet. See also TCP/IP.

META Information

The term meta can literally mean “on top of,” or “one level up.” In Internet jargon, meta-information is information used to describe or index information.

In HTML, meta-information can be embedded in the heading of a file with the <META> HTML tag. These tags are ignored when a user views the page, but they are read by Internet search and indexing software (“search engines”), and determine how a page is cataloged and displayed by Web sites like google.com, altavista.com or yahoo.com.

Now, when indexed by the search engine at www.altavista.com (off-site link), a user can search for the terms, “local road research board,” and get back the result (in fact, the very first result – indicative of well chosen key words in the META tag, the body text, and title of the page):

Mn Local Road Research Board
This site is designed to provide information to local government on Local Road Research Board (LRRB) activities. It allows you to search for details..
http://www.lrrb.gen.mn.us/ • Related pages • Translate • More pages from www.lrrb.gen.mn.us [5]

Protocol

An agreed upon standard for transmitting data. A protocol describes how two pieces of software or hardware will connect (handshake), transmit data (packets), acknowledge the receipt of data, check for errors and disconnect.

Proxy Server

Larger organizations that have several employees sharing an Internet connection often employ a proxy server. A proxy server sits between users on a local area network and the Internet, and handles all of the requests for Web pages. A user requests a Web site, and the proxy server looks up the information, downloads the pages and presents the information for the user. Often, to speed up the process, the proxy server stores (caches) the information it retrieves locally. Then, instead of contacting the Web site each time a page is requested, the proxy server presents its cached copy the next time any user on the local area network requests a page from the cached site.

Page caches can become outdated if a Web site changes a page after it has been cached locally. Many proxy servers are set to periodically check the modification dates of the pages that they store, and expire the cache (get a fresh copy) when the pages are out-of-date. Most make a trade off between boosting local area network performance and keeping content fresh. Proxy servers can also make keeping track of visitors difficult (see Section 4.0 - Measuring Success).

Raster Image

An image made up of pixels. GIF, PNG and JPEG are examples of raster image formats. Raster images are generally used to display photographs, and images that have smooth transitions in tone color and contrast.

SGML

SGML is the Standard Generalized Markup Language defined by ISO 8879. SGML was developed to be a standard, vendor-independent format for storing structured documents.

Structured Query Language (SQL)

SQL (most often pronounced See’ quell) was initially developed at IBM as a language for storing, indexing and extracting information in a database independent manner. The American National Standards Institute’s version of SQL (ANSI SQL) was proposed as the standard language for a Relational Database Management System (RDMS – Oracle, MS SQL Server, MySQL and Sybase are examples of such systems).[6] While it has gained acceptance, each RDMS implements its own version of SQL, most often starting with ANSI SQL and building on.

TCP/IP

An abbreviation for Transmission Control Protocol/Internet Protocol, TCP/IP is a suite (or “stack”) of protocols that used to connect computers together. The two main protocols TCP and IP, and sub-protocols such as HTTP and FTP, are used to connect the network of computers that make up the Internet. TCP controls how the data is sent and is used to format the data into “packets” of information. IP controls the addressing scheme that the Internet – and most other types of networks – uses. TCP/IP is a part of every major network server platform, making it the de facto international standard for networking.

Telnet

A TCP/IP sub-protocol, Telnet is used to connect a user’s computer to a server using TCP/IP and issue commands to control the server remotely. Most often used to remotely connect clients to a Web server on a UNIX platform. Telnet access is usually essential for developing interactive content on a UNIX Web server.

URI

URI is an abbreviation for Uniform Resource Identifier. A Uniform Resource Identifier is a way to refer to an object (server, router, document, image file, etc.) on the World Wide Web. A Uniform Resource Locator (URL) – or Internet Address – is one type of URI.

URL

A Uniform Resource Locator (URL) is an address for a document on the World Wide Web. A URL has two components: the first identifies the protocol to use; the second defines the IP address of the computer and the document on that computer to fetch.

Vector Image

A vector image is an image made up of vectors – mathematical representations of polygons. CAD programs, Adobe Illustrator and other drawing packages use a vector-based graphics format. In general, vector images are used for maps, schematics and similar types of drawings, and are not suitable for photographs or other images that require subtle changes in tone, contrast and color. None of the W3C core standards support vector-based graphics. A new draft recommendation, SVG (Scalable Vector Graphics), will add support for vector graphics to the Web.

World Wide Web

The complete set of documents residing on all Internet servers that use the HTTP protocol, accessible to users via a simple point-and-click system. [7]

[4] Popularity is measured by installations of the software, not by any attempt at quantifying user experience or satisfaction.

[6] When it comes to abbreviations and acronyms, database programmers rule. Only a database programmer can combine ANSI, SQL, RDMS, MS SQL and ISO in the same sentence, and have it make sense to his peers.

[7] The American Heritage® Dictionary of the English Language, Fourth Edition (Online Edition); copyright © 2000 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

A.3 Glossary of Technical Terms

Active-X