QR code, type “URL” (link to a website)
This QR content type is probably the most used one. The QR code just contains the address of a website. By scanning the code, the website can be access by the user without the hassle of manually entering the address (URL). This works because the QR reader recognizes the http(s):// protocol prefix and then interprets the text as a website address / URL.
QR code content format
Just a complete website URL. It is really important to specify the protocol to use (so never omit http:// or https://).
protocol (e.g. http://) is missing.
Content: Please visit out website: http://example.com/
Combining a URL with common text works with many QR code readers, but it is not recommended and complicates accessing your website (reductio ad absurdum as this is a problem the QR code should solve).
Nearly every mobile reader supports the URL content type, even very old software can deal with this kind of QR code. However, using this QR code only makes sense if the target reading devices provide Internet access.
You may want to shorten very long URLs by using a service like bitly. Many mobile phone readers scan “smaller” QR codes faster then codes with much content.