Browsers: The different web browsers (and their different versions) display HTML in different ways. Browsers have propriety HTML tags (e.g. <LAYER> is supported only in Navigator, <BGSOUND> is supported only in Explorer). Browsers have incompatible implementations of new technologies (e.g. DHTML, JavaScript, Style Sheets). Developers need to be aware of how web pages will render on different browsers and on different platforms (e.g. Macintosh, Windows). Netscape Navigator and Microsoft Internet Explorer dominate the browser market. Developer resources are available for each.

Design Strategies: Web designers must adopt an appropriate design approach to deal with browser issues. There are a number of possibilities.

• Common Denominator: make web pages accessible to all (i.e. use only safest HTML standards).
• Current Version: use the latest technologies (i.e. pages will only work on newest browsers).
• Compromise: use current technologies but implement them so they are still functional on limited browsers (i.e. they degrade gracefully).
• Multiple Versions: create different versions of site and allow user to select or automatically serve appropriate version (a labor intensive approach).

HTML Validation: Services are available to check web sites for browser compatibility and for correct HTML code. Some HTML editors will also check for browser compatibility.

Display Issues: Web page design must account for the variety of displays available, including monitor size and resolution, color and platform. Issues to be considered include gamma settings(2.2 for Windows and 1.8 Mac), web safe color palette and graphic file formats.

Usability Issues: Web page design should concern issues of usability such as download speed, navigation, page size and consistency.

Web Server: A program that handles requests for information from browsers. It allows HTML documents to be linked across a network. Browsers (clients) and servers communicate using a network protocol (e.g. HTTP, FTP). The terms "server-side" and "client-side" refer to which program is doing the processing.

HyperText Markup Language (HTML): The language used to create Web pages. It describes the structure and presentation of Web pages as interpreted by browsers. HTML gives authors the means to publish online documents with text formatting, lists, images, tables, frames, forms, media and links. HTML standards are developed by the World Wide Web Consortium (W3C).

Dynamic HTML (DHTML): The interaction of several technologies, including HTML, Cascading Style Sheets (CSS), JavaScript and the Document Object Model (DOM), to create web pages that are dynamic, i.e. pages with elements that change or respond to user input. DHTML encompasses text that changes color when the mouse moves over it, animations flying on and off the screen and sites that act like operating systems.

Cascading Style Sheets (CSS): Provide layout and presentation control for web documents. Style sheets simplify HTML markup and largely relieve HTML of the responsibilities of presentation. They give both authors and users control over the presentation of documents (e.g. font information, alignment, colors, positioning). Style information can be specified for individual elements or groups of elements. Style information may be specified in an HTML document or in external style sheets that can be shared.

JavaScript: An interpreted programming language used for web programming. Scripts are interpreted programs that add interactivity to web documents. Through scripts, authors may create dynamic Web pages (e.g. "smart forms" that react as users fill them out, highly interactive pages, dynamic objects) and use HTML as a means to build networked applications. JavaScript is the most popular scripting lanuage.

Document Object Model (DOM): A description of the structure of an HTML document. Contains a hierarchical representation of all objects in document (e.g. images, frames and style sheets). These objects can be operating on by programs and scripts to create dynamic content.

Extensible Markup Language(XML): A markup language used to describe any kind of data. Similar to HTML, XML makes use of tags (words bracketed by '<' and '>') and attributes (of the form name="value"), but while HTML specifies what each tag and attribute means (and often how the text between them will look in a browser), XML uses the tags only to delimit pieces of data, and leaves the interpretation of the data completely to the application that reads it. XML gives the ability to define new tags and attributes.

Design Issues: Web design is about DESIGN. Organization, form and composition of elements and content to create a coherent visual whole and an effective site.