From Seo Wiki - Search Engine Optimization and Programming Languages
Webpages may be retrieved from a local computer or from a remote web server. The web server may restrict access only to a private network, e.g. a corporate intranet, or it may publish pages on the World Wide Web. Webpages are requested and served from web servers using Hypertext Transfer Protocol (HTTP).
Webpages may consist of files of static text stored within the web server's file system (static webpages), or the web server may construct the (X)HTML for each webpage when it is requested by a browser (dynamic webpages). Client-side scripting can make webpages more responsive to user input once in the client browser.
Color, typography, illustration and interaction
Webpages usually include information as to the colors of text and backgrounds and very often also contain links to images and sometimes other media to be included in the final view. Layout, typographic and color-scheme information is provided by Cascading Style Sheet (CSS) instructions, which can either be embedded in the HTML or can be provided by a separate file, which is referenced from within the HTML. The latter case is especially relevant where one lengthy stylesheet is relevant to a whole website: due to the way HTTP works, the browser will only download it once from the web server and use the cached copy for the whole site. Images are stored on the web server as separate files, but again HTTP allows for the fact that once a webpage is downloaded to a browser, it is quite likely that related files such as images and stylesheets will be requested as it is processed. An HTTP 1.1 web server will maintain a connection with the browser until all related resources have been requested and provided. Web browsers usually render images along with the text and other material on the displayed webpage.
Web users with disabilities often use assistive technologies and adaptive strategies to access webpages. 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 webpage designer and may apply their own CSS styling to the page.
Elements of a webpage
A webpage, 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 webpage.
- For "on page" interaction:
- For "between pages" interaction:
- Hyperlinks: standard "change page" reactivity.
- Forms: providing more interaction with the server and server-side databases.
- Internal (hidden) information:
- Linked Files through Hyperlink (Like DOC,XLS,PDF,etc).
- 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).
- Note: on server-side the webpage may also have "Processing Instruction Information Items".
The webpage 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.
Webpages will often require more screen space than is available for a particular display resolution. Most modern browsers will place scrollbars (the bar at the side of the screen that allows you to move down) in the window to allow the user to see all content. Scrolling horizontally is less prevalent than vertical scrolling, not only because those pages do not print properly, but because it inconveniences the user more so than vertical scrolling would (because lines are horizontal; scrolling back and forth for every line is much more inconvenient than scrolling after reading a whole screen; also most computer keyboards have page up and down keys, and many computer mice have vertical scroll wheels, but the horizontal scrolling equivalents are rare).
When webpages are stored in a common directory of a web server, they become a website. A website will typically contain a group of webpages that are linked together, or have some other coherent method of navigation. The most important webpage to have on a website is the index page. Depending on the web server settings, this index page can have many different names, but the most common is
index.html. When a browser visits the homepage for a website, or any URL pointing to a directory rather than a specific file, the web server will serve the index page to the requesting browser. If no index page is defined in the configuration, or no such file exists on the server, either an error or directory listing will be served to the browser.
When creating a webpage, it is important to ensure it conforms to the World Wide Web Consortium (W3C) standards for HTML, CSS, XML and other standards. The W3C standards are in place to ensure all browsers which conform to their standards can display identical content without any special consideration for proprietary rendering techniques. A properly coded webpage is going to be accessible to many different browsers old and new alike, display resolutions, as well as those users with audio or visual impairments.
Typically, webpages today are becoming more dynamic. A dynamic webpage is one that is created server-side when it is requested, and then served to the end-user. These types of webpages typically do not have a permalink, or a static URL, associated with them. Today, this can be seen in many popular forums, online shopping, and even on Wikipedia. This practice is intended to reduce the amount of static pages in lieu of storing the relevant webpage information in a database. Some search engines may have a hard time indexing a webpage that is dynamic, so static webpages can be provided in those instances.
Viewing a webpage
In order to graphically display a webpage, a web browser is needed. This is a type of software that can retrieve webpages from the Internet. Most current web browsers include the ability to view the source code. Viewing a webpage in a text editor will also display the source code, not the visual product.
Creating a webpage
The design of a webpage is highly personal. A design can be made according to one's own preference, or a premade web template can be used. Web templates let webpage designers edit the content of a webpage without having to worry about the overall aesthetics. Many people publish their own webpages using products like Geocities from Yahoo, Tripod, or Angelfire. These web publishing tools offer free page creation and hosting up to a certain size limit.
Saving a webpage
While one is viewing a webpage, a copy of it is saved locally; this is what is being viewed. Depending on the browser settings, this copy may be deleted at any time, or stored indefinitely, sometimes without the user realizing it. Most GUI browsers will contain all the options for saving a webpage more permanently. These include, but are not limited to:
- Saving the rendered text without formatting or images - Hyperlinks are not identified, but displayed as plain text
- Saving the HTML file as it was served - Overall structure will be preserved, although some links may be broken
- Saving the HTML file and changing relative links to absolute ones - Hyperlinks will be preserved
- Saving the entire webpage - All images will be saved, as well as links being changed to absolute
- Saving the HTML file including all images, stylesheets and scripts into a single MHTML file. This is supported by Internet Explorer, Firefox and Opera. Firefox only support this if the MAF plugin has been installed. An MHTML file is based upon the MHTML standard.
Common web browsers, like Mozilla Firefox, Internet Explorer and Opera, give the option to not only print the currently viewed webpage to a printer, but optionally to "print" to a file which can be viewed or printed later. Some webpages are designed, for example by use of CSS, so that hyperlinks, menus and other navigation items, which will be useless on paper, are rendered into print with this in mind. Space-wasting menus and navigational blocks may be absent from the printed version; other hyperlinks may be sh the end.
- ↑ "How People with Disabilities Use the Web". W3C. 5 May 2005. http://www.w3.org/WAI/EO/Drafts/PWD-Use-Web/. Retrieved 2009-05-01.
- ↑ Tysver, Dan (1996-2008). "Linking and Liability - Problems with Frames". Minneapolis, USA: Beck & Tysver. http://www.bitlaw.com/internet/linking.html#Frames. Retrieved 2009-05-01.
- ↑ Frames Problems - ITC Web Development
- ↑ 4.0 4.1 "HTML Techniques for Web Content Accessibility Guidelines 1.0 - Frames". W3C. 6 November 2000. http://www.w3.org/TR/WCAG10-HTML-TECHS/#frames. Retrieved 2009-05-01. "In the following sections, we discuss how to make frames more accessible. We also provide an alternative to frames that uses HTML 4.01 and CSS and addresses many of the limitations of today's frame implementations."
- ↑ Steinmetz, Israel (2 November 1999). "Frames Free!". http://www.noframes.org/. Retrieved 2009-05-01.