Linux did not appear in a vacuum. It inherits ideas from Unix (1969+) — an OS built at Bell Labs around simplicity, text streams, and multi-user design. In 1991 Linus Torvalds, then a student in Finland, released a small kernel as a hobby project for 386 PCs. It combined with GNU tools and the burgeoning Internet to become the collaborative operating system we know today.

The GPL lets anyone study, modify, and redistribute the kernel as long as derivative works shared in certain ways also stay open. That legal framework aligned with student labs, corporate contributors, and volunteers contributing patches by email and later Git. Without a permissive collaboration model at scale, growth would have been slower.