- [[Kernel]] - [[Unix]] - [[Linux]] - [[Shell]] - [[OS Bootup]] - [[Processes]] - [[Virtual Memory]] - [[Memory Management]] - [[Endianness]] - most important piece of [[👨‍💻 SOFTWARE ENGINEERING|Software]] on a [[💽 COMPUTER ENGINEERING|Computer]], since it's what we interact with, & it controls how all the other [[Programming|Programs]] are run on [[💽 COMPUTER ENGINEERING|Computers]] - key engineering challenge