What is the purpose of using $_SERVER['HTTP_USER_AGENT'] in PHP?

The purpose of using $_SERVER['HTTP_USER_AGENT'] in PHP is to retrieve the User-Agent header sent by the client's browser. This information can be used to identify the type of browser and device being used to access the website, allowing for customized content or functionality based on the user's device. 

$user_agent = $_SERVER['HTTP_USER_AGENT'];

if (strpos($user_agent, 'MSIE') !== false) {
    echo "You are using Internet Explorer.";
} elseif (strpos($user_agent, 'Firefox') !== false) {
    echo "You are using Firefox.";
} elseif (strpos($user_agent, 'Chrome') !== false) {
    echo "You are using Chrome.";
} else {
    echo "Unable to detect your browser.";
}

Keywords

$_SERVER HTTP_USER_AGENT PHP user agent browser detection

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