AutoCAD 64-bit portable is a version of AutoCAD that has been optimized to run on 64-bit operating systems without the need for installation. This means you can carry the software with you on a USB drive or any portable storage device, making it incredibly easy to work on different computers without leaving a footprint. The 64-bit architecture allows for better performance and the ability to handle larger files and more complex projects compared to its 32-bit counterpart.