What is a defining characteristic of Free Software?

Free Software is defined primarily by its freedom for users to run, modify, and share the software. The defining characteristic is that it can be modified by anyone who uses it, which encompasses several important concepts: the ability to access the source code, make alterations to that code, and share those modifications with others. This freedom is crucial as it promotes collaboration, innovation, and transparency in software development.

While free software is often available at no cost, the emphasis on "free" pertains to freedom rather than merely the price tag. This is a common misconception, as some free software may come with a charge, but its freedoms remain intact. The focus on modification reflects the ethos of open source development, where users can tailor the software to their specific needs and contribute back to the community.

Moreover, the notion that free software might require subscriptions for updates or can only be used for non-commercial purposes contradicts the core principles that govern free software. These characteristics undermine the very freedoms that define what free software is intended to be, making option B the most accurate depiction of its essence.