Linux kernel version 1.0 was released in 1994.
The milestone release appeared in March 1994, marking the point at which Linus Torvalds and the growing developer community considered the kernel mature enough for production use. Linux had begun as a small 1991 project inspired by Unix and Minix, but development accelerated rapidly as programmers around the world contributed drivers, networking support, filesystems, and other improvements.
Version 1.0 was much more capable than the earliest releases. Linux 0.01 was not even independently buildable, while version 0.11, released in December 1991, was the first self-hosting version. By 1.0, the kernel had more than 170,000 lines of source code and could support a broad range of PC hardware and Unix-like software.
A common mix-up is confusing Linux 1.0 with Linux 2.0. The latter arrived in 1996 and added important features including symmetric multiprocessing, but it was not the first stable production milestone.