First things first, lets explain what SEO friendly web URLs can do.

1. They promote traffic as /home/ is easier to remember than index.php?page=home
2. They are easier for search engines to crawl, some search engines refuse to crawl anything after the ?
3. They are easier to maintain and keep permanent (even if you update your scripts).
4. They hide the chosen programming language from the visiting users.

All you require is an Apache webserver (common among webhosts) & a basic knowledge of PHP.
Lets take a look at my first example, create a file called ‘.htaccess‘ (period then htaccess):

# These hashes are comments, they will explain what I am doing.
# First things first, lets turn on the Rewrite Engine
RewriteEngine On
# Then lets define some rules
RewriteRule ^([a-z0-9]+)/$ /index.php?page=$1 [NC,L]

The brackets/parenthesis are used to start a variable, variables are stored in order and are numeric, this is used and referred to later in the Rule using a $1. The [a-z0-9] signifies it can be any alphabetic or numeric character, and the plus+ symbol means it has to be more than one character long. I used a-z0-9 instead of a global (.*) which matches anything because I consider it more secure.

The ^ and $ are a standard regular expression and signify beginning and end, so the user cannot add anything else, (aka. /home/blaaaa would be invalid) and the index.php?page=$1 points back to index.php. At the end of the line, parameters or options are defined. In this case NC stands for Case InSensItIvE and the L stands for Last Rule, so if that rule is triggered, no others are.

This example turns http://www.domain.com/downloads/ into http://www.domain.com/index.php?page=downloads.
If you would like to read up on index.php?page= methods, please review “Advanced Navigation using Includes“.

Other resources I found useful:

• Mod Rewrite Cheat Sheet (Great to print out)
• Apache docs on Mod Rewrite (For the more advanced)

Hope you enjoyed this tutorial.

Written in php4, works in php5, mostly so you can view the source and attempt at understanding how it works.

/*--- Configuration ---*/
 
$page = Array();
 
// Edit these vars or leave as is.
 
$page['home'] = "home";
 
// Replace this with the default or main page.
 
$page['error'] = "404";
 
// Replace this with the 404 page, can be 'home' also or even $page['home'].
 
$page['format'] = ".php";
 
// This will be the format of your page so ?page=bla will be bla.php.
 
$page['trig'] = "page";
 
// The trigger used so ?page=bla.
 
/*--- Do not edit below! ---*/if (empty($_GET[($page['trig'])])) {
 
$pg = $page['home'].$page['format'];
 
} elseif (!ctype_alpha($_GET[($page['trig'])])||!file_exists($_GET[($page['trig'])].$page['format'])) {
 
$pg = $page['error'].$page['format'];
 
} else {
 
$pg = $_GET[($page['trig'])].$page['format'];
 
}
 
include($pg);

ctype_alpha is used to make sure the “page” passed by the user only contains characters A-Z for security (so people can’t include /etc/passwd for example).

file_exists is used to determine whether the page + extension actually exist and if they don’t, the error page is then thrown.

An idea, if you want a readable page name from $pg, you could try

$page_name = ucwords(basename($pg,  $page['format']));

If you have any further questions, please do not hesitate to leave a comment,
I will update this snippet when features are suggested or questions and comments made.