They are useful for granular tracking (e.g. If you send a link to a resume and you want to make they have read it).
if you have a long URL you want to turn into a QR-Code, using a URL shortener will decrease the complexity of the Code (=improve the readabilty), while allowing you to track how many people scanned it and on top of that you can change which site it is pointing to without redirects or reprints.
They are useful for granular tracking (e.g. If you send a link to a resume and you want to make they have read it).
if you have a long URL you want to turn into a QR-Code, using a URL shortener will decrease the complexity of the Code (=improve the readabilty), while allowing you to track how many people scanned it and on top of that you can change which site it is pointing to without redirects or reprints.