How do I redirect someone from where they visit me from?

[progex]

For example, if the visitor comes from the search term "widgets" in Google, how would I change the content on a page so that it targets the "widget" category.

Redirecting may be dangerous in terms of SEO, so is there a way to display dynamic content according to where the visitor comes from?

I've seen a particular site do this, however, the extension on the landing page is .html. If need be, I will sticky you the URL of the page so that you can see it in "detail".

[jatar_k]

Well, for starters, you can set up apache so that the html extension is parsed for php using htaccess or just httpd.conf using something like

addtype application/x-httpd-php .php .html

For the dynamic serving based on referer data you could analyze the referer using $_SERVER['HTTP_REFERER'] [ca.php.net] and then include content based on parsing the query string.

I use this piece for an apache log parser to chop up query strings. This catches most of the query strings and grabs out the keywords and increments a keyword array. This is pulled from a large script so it may have some unrelated vars in there but it does work quite well.

It does a ton of other stuff at the beginning but these lines are relevant

$line = fgets($fp)
$qusplit = split('"',$line);
$queryarr = parse_url($qusplit[3]);

these are used because it needs to get the referer from the logfile in your case it could be

$queryarr = parse_url($_SERVER['HTTP_REFERER']);

if (!empty($queryarr['query'])) { 
 parse_str($queryarr['query'],$breakuparr); 
 if (isset($breakuparr['encquery'])) { 
 $qs = $breakuparr['encquery']; 
 } else if (isset($breakuparr['q'])) { 
 $qs = $breakuparr['q']; 
 } else if (isset($breakuparr['p'])) { 
 $qs = $breakuparr['p']; 
 } else if (isset($breakuparr['source']) && $breakuparr['source']!= "NSCPTop") { 
 $qs = $breakuparr['source']; 
 } else if (isset($breakuparr['query'])) { 
 $qs = $breakuparr['query']; 
 } else if (isset($breakuparr['Keywords'])) { 
 $qs = $breakuparr['Keywords']; 
 } else if (isset($breakuparr['cid']) && isset($breakuparr['s'])) { 
 $qs = $breakuparr['s']; 
 } else { 
 $qs = ""; 
 } 
 // end query finding stuff 
 $qs = strtolower(trim($qs)); 
 if (!empty($qs)) { 
 $qs = str_replace('\"','',$qs); 
 $qs = str_replace('+','',$qs); 
 } 
}