Portable software refers to applications that are designed to run on a computer without needing to be installed on the system's hard drive. These programs can be executed from external storage devices such as USB flash drives, external hard drives, or cloud storage. The primary advantage of portable software is its flexibility and convenience; users can carry their essential applications and data with them and use them on different computers without leaving a footprint on the host system. This makes portable software an ideal solution for people who need to work on multiple computers or those who want to keep their systems clutter-free.