What is this? This is a QR Code: a machine-readable image-based code consisting of black and white squares. QR Codes are typically used for storing URLs and other information for reading by a smart devices like smart phones.
When scanned by an appropriate app on your mobile device, you are redirected to the embedded URL of this page. View this page with one device (desktop or another mobile device), and then scan the
QR Code with your mobile device. This makes it quicker and easier to browse a page discovered on one device on your mobile device without manually entering the URL in the mobile device browser address bar.
⚬ If you are using an Android phone, you can find a QR Code reading app at Google Play on your device.
⚬ If you are using an iOS device (iPhone, iPad, etc.), you can find a QR Code reading app at the Apple iTunes App Store on your device.
⚬ If you are using a Windows phone, you can find a QR Code reading app at the Microsoft Store on your device.
PHP transparently supports HTTP cookies. Cookies are a mechanism for
storing data in the remote browser and thus tracking or identifying return
users. You can set cookies using the setcookie() or
function. Cookies are part of the HTTP header, so
setcookie() must be called before any output is sent to
the browser. This is the same limitation that header()
has. You can use the output buffering
functions to delay the script output until you have decided whether
or not to set any cookies or send any headers.
Any cookies sent to you from the client will automatically be included into
a $_COOKIE auto-global
array if variables_order
contains "C". If you wish to assign multiple values to a single
cookie, just add  to the cookie name.
Depending on register_globals,
regular PHP variables can be created from cookies. However it's not
recommended to rely on them as this feature is often turned off for the
sake of security.