1. Kernel: This is the core of the operating system which manages system resources, interacts with hardware, and provides basic services for all other parts of the system. For example, the Linux kernel.
2. System Utilities: These are programs that help manage the system and provide useful functions. Examples include utilities such as ls, cp, mv, and chmod.
3. Shell: This is the interface between the user and the operating system. It interprets commands and passes them to the kernel. Common shells include bash, csh, and zsh.
4. File System: This is the structure used to organize and store files and directories. Examples include ext4, xfs, and btrfs.
5. Networking: This is how the computer communicates with other computers. Examples include TCP/IP, NFS, and SSH.