MCS-170 The Nature of Computer Science

Chapter 2 - Part I

A Web page is a document that contains formatting information in HyperText Markup Language (HTML)
A Web browser (e.g., Internet Explorer or Firefox) accesses a Web page, interprets the formatting information, and displays the formatted page.
A Uniform Resource Locator (URL) is a name for a Web page on the Internet (e.g., http://www.gac. edu/~sskulrat/index.html).
URL consists of: protocol://name of Web server/directory/name of page

HTML is a document formatting language
A Web browser formats the display of a page according to HTML instructions called tags
An HTML tag is a string of characters surrounded by angle brackets

Tags are like on/off switches for styles of formatting. In most cases, an "on" tag (i.e. <head>) needs a closing ("off") tag at its end (i.e. </head>).
Many tags can be "on" at one time, but no "on" tag may overlap on "off" tag. For example, bold text bold and italics text just italics text is an invalid HTML instruction, as the on tag is not closed off before the preceding tag is closed. A correct form of this would be bold text bold and italics text just italics text. Indentation when creating HTML code can help keep such errors at a minimum:

<p>
    <b>
        bold text
        <i>
            bold and italics text
        </i>
    </b>
    <i>
        just italics text
    </i>
</p>

Comments. These are single tag elements, starting with . Example:
Breaks: These are single tag elements of the form . This tag forces text to move to the next line.

In HTML formatting, the default method of formatting is to have exactly one space between words or characters. The only way to make more than one space is to use the 'non breaking space' symbol

Each html page should consist of two sections: the head, where general information about the page is specified (like the title, for example), and the body, where the text or images that the user is going to see are specified.

HTML tags	What they are used for
<html>	begin html document
<head>	begin document head
<title>	begin title
actual page title
</title>	end title
</head>	end document head

<body>	begin document body
text and images will be written here
</body>	end document body

</html>	end HTML

Formatting tag	Use	Does it need a closing tag?
<center>	used to center a section of text or images	YES
<p>	begin paragraph (a blank line will be left between paragraphs)	YES
<div>	Division Tag, like a paragraph but more flexible. Can be used to combine multiple page elements as one group	YES
<h1>	begin heading type 1. (Large Heading) also h2, h3, h4, etc.	YES
<b>	begin bold text	YES
<i>	begin italics text	YES
<u>	begin underline text	YES
<sub>	begin subscript text	YES
<sup>	begin superscript text	YES
<s>	put a cross-out line through the text	YES
<span>	define an area of text within a paragraph	YES
<br>	breaks the line and puts the rest on the next line without a blank line	NO
<hr>	horizontal line acroos the width of the browser window	NO
<a>	begin hyperlink--form is <a href="ADDRESS">Text for label</a> Example: <a href="http://www.amazon.com">Books</a>	YES
<img>	inage tag--form is <img src="ADDRESS" alt="text description"/> Example: <img src="bugs.gif" alt="Bugs Bunny Image"/> Note: GIF or JPEG images only	NO
STYLE Parameter Examples (used inside a tag)
style = "color:blue" style = "text-align:right"	used to affect style of text--change font colour or alignment (or other style attributes) Example: <p style ="text-align:right"> starts a paragraph section that will be right aligned. Example: <span style="color:red"> starts a span of text that will be colored red.	NO - used inside of a tag