The Linux kernel is a free and open-source, monolithic, Unix-like operating system kernel. It was conceived and created in 1991 by Linus Torvalds. Linux kernels have different support level depending on version, (e.g. version 4.4, released in January 2016, was declared to have Long-Term Support (LTS)). It has six years of support that way, but it was also defined to have Super Long Term Support (SLTS), i.e. Civil Infrastructure Platform will provide support (for 32-bit ARM and x86-64 only) until at least 2026, possibly until 2036. It is by now the oldest supported version.