Linking

Sr.No.
Topics
1

Relative Pathnames Vs. Absolute Pathnames
2
 URLs
3
 Links to Specific Sections
4
 Mailto

 

The chief power of HTML comes from its ability to link text and/or an image to another document or section of a document. A browser highlights the identified text or image with color and/or underlines to indicate that it is a hypertext link (often shortened to hyperlink or just link).

HTML's single hypertext-related tag is <A>, which stands for anchor. To include an anchor in your document:

  1. start the anchor with <A (include a space after the A)
  2. specify the document you're linking to by entering the parameter HREF="filename" followed by a closing right angle bracket (>)
  3. enter the text that will serve as the hypertext link in the current document
  4. enter the ending anchor tag: </A> (no space is needed before the end anchor tag)

Here is a sample hypertext reference in a file called US.html: 

    <A HREF="index.html">Home Page</A>

This entry makes the word Home Pagethe hyperlink to the document index.html, which is in the same directory as the first document.

Relative Pathnames Versus Absolute Pathnames

You can link to documents in other directories by specifying the relative path from the current document to the linked document. For example, a link to a file abc.html located in the subdirectory other websites would be: 

    <A HREF="other websites/abc.html">test file</A>

These are called relative links because you are specifying the path to the linked file relative to the location of the current file. You can also use the absolute pathname (the complete URL) of the file, but relative links are more efficient in accessing a server. They also have the advantage of making your documents more "portable" -- for instance, you can create several web pages in a single folder on your local computer, using relative links to hyperlink one page to another, and then upload the entire folder of web pages to your web server. The pages on the server will then link to other pages on the server, and the copies on your hard drive will still point to the other pages stored there.

It is important to point out that UNIX is a case-sensitive operating system where filenames are concerned, while DOS and the MacOS are not. For instance, on a Macintosh, "DOCUMENT.HTML", "Document.HTML", and "document.html" are all the same name. If you make a relative hyperlink to "DOCUMENT.HTML", and the file is actually named "document.html", the link will still be valid. But if you upload all your pages to a UNIX web server, the link will no longer work. Be sure to check your filenames before uploading.

Pathnames use the standard UNIX syntax. The UNIX syntax for the parent directory (the directory that contains the current directory) is "..".

If you were in the abc.html file and were referring to the original document index.html, your link would look like this: 

    <A HREF="../index.html">Home Page</A>
In general, you should use relative links whenever possible because
  1. it's easier to move a group of documents to another location (because the relative path names will still be valid)
  2. it's more efficient connecting to the server
  3. there is less to type

However, use absolute pathnames when linking to documents that are not directly related. For example, consider a group of documents that comprise a user manual. Links within this group should be relative links. Links to other documents (perhaps a reference to related software) should use absolute pathnames instead. This way if you move the user manual to a different directory, none of the links would have to be updated.