what is the use of HDD enclosure case?

Hi
I’ve recovered a 500 GB SATA HDD from a non working PC. I want transfer all data inside it into my laptop (via USB). I’ve heard some kind of 2.5”/3.5” HDD enclosure case. But not sure what are those for. If those are the device I need then which one I need to buy 2.5” or 3.5”??

You can actually access and use hard disk that are not installed in a computer with the help of a hard drive enclosure which is an external device. And what you have mentioned that, the 2.5”/3.5” HDD enclosures are designed to be used with laptop or a desktop computer. And with a laptop enclosure you can connect a laptop hard drive to your computer by using a Firewire or a usb or a external Sata cable.

thanks techman...