What type of software is described as being free and modifiable by anyone?

The description of software that is free and modifiable by anyone aligns perfectly with Open Source Software (OSS). OSS promotes the idea that the source code is accessible to users, allowing them to view, modify, and distribute it. This characteristic fosters collaboration and innovation, as developers can enhance the software and fix bugs based on community feedback.

Open Source Software often operates under licenses that explicitly grant these freedoms, ensuring that anyone can contribute to and benefit from the program. This model contrasts sharply with other types of software, such as proprietary or commercial software, which typically restrict user access to the source code and impose limitations on modification and redistribution.

In essence, Open Source represents a collaborative approach to software development, empowering users to take control of the applications they use. This has led to the proliferation of successful projects like the Linux operating system, the Apache web server, and many others, all fueled by community involvement and shared knowledge.