Browsers

Browsers
A web browser can have a Graphical User Interface, like Internet Explorer, Mozilla Firefox and Opera, or can be text-based, like Lynx.
Web users with disabilities often use assistive technologies and adaptive strategies to access web pages.[1] Users may be color blind, may or may not want to use a mouse perhaps due to repetitive stress injury or motor-neurone problems, may be deaf and require audio to be captioned, may be blind and using a screen reader or braille display, may need screen magnification, etc.
Disabled and able-bodied users may disable the download and viewing of images and other media, to save time, network bandwidth or merely to simplify their browsing experience. Users of mobile devices often have restricted displays and bandwidth. Anyone may prefer not to use the fonts, font sizes, styles and color schemes selected by the web page designer and may apply their own CSS styling to the page.
The World Wide Web Consortium (W3C) and Web Accessibility Initiative (WAI) recommend that all web pages should be designed with all of these options in mind.

Elements of a web page
A web page, as an information set, can contain numerous types of information, which is able to be seen, heard or interact by the end user:
Perceived (rendered) information:
Textual information: with diverse render variations.
Non-textual information:
Static images on raster graphics, typically GIF, JPEG or PNG; or vector formats as SVG or Flash.
Animated images typically Animated GIF and SVG, but also may be Flash, Shockwave, or Java applet.
Audio, typically MIDI or WAV formats or Java applets.
Video, WMV (Windows), RM (Real Media), FLV (Flash Video), MPG, MOV (Quicktime)
Interactive information: more complex, glued to interface; see dynamic web page.
For "on page" interaction:
Interactive text: see DHTML.
Interactive illustrations: ranging from "click to play" image to games, typically using script orchestration, Flash, Java applets, SVG, or Shockwave.
Buttons: forms providing alternative interface, typically for use with script orchestration and DHTML.
For "between pages" interaction:
Hyperlinks: standard "change page" reactivity.
Forms: providing more interaction with the server and server-side databases.
Internal (hidden) information:
Comments
Metadata with semantic meta-information, Charset information, Document Type Definition (DTD), etc.
Diagramation and style information: information about rendered items (like image size attributes) and visual specifications, as Cascading Style Sheets (CSS).
Scripts, usually JavaScript, complement interactivity and functionality.
Note: on server-side the web page may also have "Processing Instruction Information Items".
The web page can also contain dynamically adapted information elements, dependent upon the rendering browser or end-user location (through the use of IP address tracking and/or "cookie" information).
From a more general/wide point of view, some information (grouped) elements, like a navigation bar, are uniform for all website pages, like a standard. These kind of "website standard information" are supplied by technologies like web template systems.