Redox OS is an operating system with a microkernel design that aims to be secure, usable, and free. Redox is
implemented in Rust because of Rust's focus on safety and performance.
Redox is not just a kernel, it's a full-featured Operating System, providing packages (memory allocator, file system, display manager, core utilities, etc.) that together make up a functional and convenient operating system. You can loosely think of it as the GNU or BSD ecosystem, but in a memory safe language and with modern technology. See this list for overview of the ecosystem.