AN INTRODUCTION TO HTML

HYPERTEXT LINKS

<A>, </A> Anchors

An anchor associates a region of images and text with an action.

The most common type of anchor creates a clickable region tied to an action. The action is performed when a user clicks within the defined region.

All anchor elements contain two critical sections:

• The action to occur
• The region (usually clickable) of images and text associated with the action

	<A (action to occur) > (clickable region) </A>  

Some of the possible actions:

1. Fetch a new HTML document
2. Establish a position marker within an HTML document
3. Seek to a specified position marker within an HTML document
4. Fetch an image file
5. Start a telnet session
6. Start a ftp session
7. Start a gopher session
8. Compose an email message
9. Load a file from the local disk

Examples (in the same sequence as the previous list):

1. <A HREF="http://www.secs.csun.edu/">School of Engr and Comp Sci</A>
2. <A NAME="examples">Here are some examples:</A>
3. <A HREF="#examples">(see examples in this document)</A>
4. <A HREF="http://www.csun.edu/~sgs/me.gif">click to see my picture</A>
5. <A HREF="telnet://huey.csun.edu">click to connect to huey</A>
6. <A HREF="ftp://gatekeeper.dec.com/pub/">establish an ftp connection</A>
7. <A HREF="gopher://gopher.csun.edu">see gopher pages</A>
8. <A HREF="mailto:sgs@secs.csun.edu">send email</A>
9. <A HREF="file:///volume/directory/file">load a local file</A>

<IMG> Images

Images can be included in HTML documents. The most common image format supported by HTML is GIF (Graphical Interchange Format).

All image elements contain information on:

• Where the image is located
• The image type (denoted by the file name extension)
• Alignment information
• Text to be displayed if the image cannot be loaded

	<IMG SRC=". . ."  ALIGN=. . .   ALT=". . ." >  

The alignment options are TOP, BOTTOM (default), and MIDDLE. The position alignment is in terms of the current line of text.

Some browsers also support alignment options of LEFT and RIGHT with the text flowing down the opposite side of the image. Use <BR CLEAR=. . .> with CLEAR set to LEFT or RIGHT to terminate special alignment.

Examples:

• <IMG SRC="http://www.csun.edu/~sgs/me.gif" ALT="[my picture]">
• <IMG SRC="http://www.csun.edu/~sgs/stamp.gif" ALIGN=TOP>
• <A HREF="big.gif"> <IMG SRC="small.gif"> (see a bigger version)</A>

Some anchors and images to click on:

• Click on the image to view a larger version of this gif file
• Click on this line to load an HTML page that illustrates image alignment options

Source for the previous example:

    <P>Some anchors and images to click on:
    <UL>
    <LI><A HREF="big.gif"><IMG SRC="small.gif">Click on the image</A> 
    to view a larger version of this gif file
    <LI><A HREF="images.html">Click on this line to load an HTML page that
    illustrates image alignment options</A>
    </UL>