The "64-bit" designation refers to the memory architecture. A 64-bit version of software can utilize more than 4GB of RAM. This is vital for heavy Visio projects—complex engineering diagrams or massive network topology maps with thousands of shapes—which would likely crash a 32-bit application due to memory limitations.

In the software world, "portable" refers to a version of a program that does not require installation. You simply download a folder or an executable file, click it, and the program runs. It leaves no traces in the Windows Registry and can be run from a USB thumb drive. This is popular for users who switch computers often or do not have administrative rights to install software on a work machine.

Microsoft Visio 2010 Portable 64 Bits refers to a modified, "no-install" version of the legacy diagramming software designed to run on 64-bit Windows operating systems. While the idea of a portable version—running directly from a USB drive without installation—is appealing for quick tasks, it carries significant risks and limitations in a modern computing environment. Understanding Microsoft Visio 2010

Because Microsoft does not offer a standalone portable version, these files are often "cracked" or modified by third parties.