- Root user is the main user running entire Linux system
- Admin accoun IS NOT THE SAME as root user. Admins are accounts of** 'wheel' **group
- Don't use typical (easy to guess) names for admin acc
- Use **Sudo **to run commands as root user
- **kdump - **Linux kernal feature that creates crash dumps in event of kernel crash
- **Boot directory **contais boot files, kernal, ram, mapping