Client/server system
A client/server system is a very keen way of distributing information across information systems like a local area network (LAN), a wide area network (WAN), or the Internet.
The "client" is actually a software program, like Firefox, that is being operated by a person who is the one who really wants to see the file.
The whole process looks something like the figure below:
The client/server protocol used by the web is HTTP (HyperText Transport Protocol)
A web browser (client software) do with a file it receives from a web server (server software).
HTML (Hyper Text Markup Language) is a very simple language used to "describe" the logical struture of a document.
HTML tags can not only define a formatting option, they can also define attributes to those options as well.
The following table outlines the HTML tags that define the basic HTML document.
| Opening Tag | Closing Tag | Description |
|---|---|---|
| <!DOCTYPE> | none | Defines the HTML specification your document uses such as <!DOCTYPE HTML PUBLIC "-/IEFT//DTD HTML 3.2//EN">. This tag will be used before the <HTML> tag. |
| <html> | </html> | Specifies that the document should be interpreted as an HTML document. This tag should either be the first line in an HTML document or should be directly after the <!DOCTYPE> specification. Likewise, the closing tag should be the last line in an HTML file. |
| <head> | </head> | Specifies an area where the browser can look to for general information about the document. It requires a <TITLE> tag at the minimum. |
| <title> | </title> | Specifies the text that will be used for the header of the browser frame. Some search engines use this text for keyword indexing and browsers will use this for naming bookmarks if a user chooses to bookmark your site. So choose your titles well. This tag goes between the <HEAD> and </HEAD> tags. |
| <base> | None | Specifies the base URL that all relative links should utilize. This helps if you move an entire site off its original server and need to quickly make all relative links work at their new locale. This tag must appear within the bounds of the <HEAD> element. You will use this tag only with corresponding HREF attribute such as <BASE HREF = "www.mydomain.com"> |
| <body> | </body> | Specifies the information that should be displayed in the browser window. This is the document itself rather than information "about" the document. The <BODY> tag takes several optional parameters that will be discussed on Day Three. |
| <!-- comment goes here--> | none | You can create comment text that will not be displayed by the browser by placing it between the <!-- and the -->. Some browsers also support the <COMMENT></COMMENT> tags. |
| <meta> | /> | Embeds information about the document. You can use the tag with
the following attributes provided you use it within the bounds of the
<HEAD> element:
<META HTTP-EQUIV = "REFRESH" CONTENT = "10; url=doc2.html" / > - Automatic redirection <META NAME = "Description" CONTENT = "a description of page" / > - Gives a search engine a description to use <META NAME = "Keywords" CONTENT = "comma separated keywords" / > - Gives a search engine help for indexing <META HTTP-EQUIV = "PRAGMA" CONTENT = "no-cache" / > - Tells the browser not to cache the page. <META HTTP-EQUIV = "expires" CONTENT = "Saturday 12 April 1997 10:23:23 GMT" / > - Tells the browser when the page expires. |
Basic HTML Tags by Example
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
<html>
<head>
<title>Hello World</title>
<meta HTTP-EQUIV = "Description" NAME = "Description"
CONTENT = "This page is simply a basic HTML page">
<meta HTTP-EQUIV = "Keywords" NAME = "Keywords"
CONTENT = "HTML, tutorial, learning, example">
</head>
<body> <!--This is a comment and comments do not show up in the browser --> This is a very simple web page </body>
</html>
This: <b><i>This text is bold and italic</i></b>
Not this: <b><i>This text is bold and italic</b></i>
This: <p>This is a paragraph</p>, A break: <br />
Not this: <p>This is a paragraph, A break: <br>
This: <body> <p>This is a paragraph</p> </body>
Not this: <BODY> <P>This is a paragraph</P> </BODY>
All XHTML elements must be nested within the <html> root element. All other elements can have sub (children) elements. Sub elements must be in pairs and correctly nested within their parent element. The basic document structure is:
<html> <head> ... </head> <body> ... </body> </html>
This: <table width="100%">Not this: <table width=100%>