For 25 years, OSI’s definition of open-source software has been widely accepted by developers who want to build on each other’s work without fear of lawsuits or licensing traps. Now, as AI reshapes the landscape, tech giants face a pivotal choice: embrace these established principles or reject them. The Linux Foundation has also made a recent attempt to define “open-source AI,” signaling a growing debate over how traditional open-source values will adapt to the AI era.