How can PHP be used to extract keywords from the HTTP_REFERER URL in a web search scenario?

To extract keywords from the HTTP_REFERER URL in a web search scenario using PHP, we can use a combination of string manipulation functions and regular expressions. We can extract the query parameter from the URL and then split it into individual keywords by splitting it on spaces or other delimiters commonly used in search queries.

// Get the referer URL
$referer = $_SERVER['HTTP_REFERER'];

// Extract the query parameter from the URL
$query = parse_url($referer, PHP_URL_QUERY);

// Extract keywords from the query parameter
if(preg_match_all('/\b\w+\b/', $query, $matches)){
    $keywords = $matches[0];
    // Now $keywords array contains individual keywords from the referer URL
    print_r($keywords);
}