How does the HTTP protocol affect the retrieval of cookies in PHP?

When using the HTTP protocol, cookies are passed from the server to the client in the response headers. In PHP, to retrieve cookies that have been set, you can use the $_COOKIE superglobal array. This array contains key-value pairs of all the cookies that have been sent by the client. 

// Retrieve a specific cookie
$cookieValue = $_COOKIE['cookie_name'];

// Check if a cookie exists before accessing it
if(isset($_COOKIE['cookie_name'])){
    $cookieValue = $_COOKIE['cookie_name'];
    // Do something with the cookie value
}

Keywords

HTTP protocol cookies retrieval PHP session management

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