Which operating system is known for its open-source license?

The operating system known for its open-source license is Linux. This means that the source code for Linux is freely available for anyone to view, use, modify, and distribute. This openness fosters a collaborative environment where developers from around the world can contribute to the improvement and evolution of the software.

Linux's open-source nature has led to the creation of numerous distributions (distros) that cater to different user needs, from general-purpose use to specialized applications. This flexibility is a major reason for its widespread adoption in various environments, including servers, desktops, and embedded systems.

In contrast, other operating systems like Windows and macOS are proprietary, meaning their source code is not available to the public, and they have restricted licensing terms. Unix, while historically influential in the development of operating systems, is also not an open-source system in the same way that Linux is, as it is governed by a variety of licensing agreements. This distinction emphasizes why Linux stands out as the correct answer in relation to open-source licenses.