Windows Hierarchical Structure

The Windows operating system hierarchy refers to the organization of system components and interfaces that work together to manage hardware, software, and user interactions. Here's an overview of the Windows hierarchy:

Hardware: The physical components of the computer, such as the CPU, memory, storage devices, and peripheral devices (keyboard, mouse, printer, etc.).

Firmware: Low-level software embedded in hardware components, such as BIOS or UEFI, which initialize hardware during the boot process.

Kernel: The core part of the operating system that manages system resources, including memory management, process management, and hardware communication.

Drivers: Software that allows the operating system to communicate with hardware devices. Device drivers translate general input/output instructions to device-specific operations.

System Services: Background processes that perform essential functions such as networking, security, and system monitoring. Examples include the Windows Update service and the Print Spooler service.

User Mode: The non-privileged mode where applications run. User mode includes:

System Processes: Essential system-level processes that provide core functionality, such as the Windows Shell (explorer.exe) and the Task Manager.

User Applications: Programs installed and run by users, such as web browsers, office suites, and games.

User Interface (UI): The visual and interactive layer that allows users to interact with the computer. This includes the desktop, taskbar, start menu, windows, icons, and control panels.

API (Application Programming Interface): Sets of routines, protocols, and tools for building software. The Windows API allows applications to interact with the operating system and other software components.

File System: Manages the storage, retrieval, and organization of files on storage devices. The most common file systems in Windows are NTFS (New Technology File System) and exFAT (Extended File Allocation Table).

Registry: A hierarchical database that stores configuration settings and options for the operating system and installed applications.

Security: Measures and components designed to protect the system and user data, including user accounts, permissions, encryption, and security policies.

C-Drive

The hierarchy of the C: drive in a Windows operating system typically follows a structured format to organize system files, user data, and application files. Here are the common folders and their purposes.

C:\ (Root Directory)

The top level of the C: drive where the main folders and files are located.

C:\Windows

Contains the operating system files, including system libraries, executables, and configuration files.

Subfolders

PerfLogs:  Performance logs created by the Performance Monitor and other diagnostic tools
System32: Critical system files and executables
SysWOW64: 32-bit system files on 64-bit Windows
Temp: Temporary files used by the system

C:\Program Files

Default directory for installing 64-bit applications.  Contains subfolders for each installed application.

C:\Program Files (x86)

Default directory for installing 32-bit applications on a 64-bit system. Contains subfolders for each installed application.

C:\Users

Contains user profile folders for each user account on the system.

Subfolders

Default: Template for new user profiles
Public: Shared files accessible by all users
[Username]: Personal folder for each use 

Subfolders

Documents
Downloads
Desktop
Music
Pictures
Videos


Hidden Files & Folders

C:\ProgramData

Stores application data and settings shared across all users.

C:\AppData (Located within each user's profile folder)

Stores user-specific application data and settings.

Subfolders

Local: Data specific to a single computer.
LocalLow: Data with lower integrity requirements.
Roaming: Data that can roam with a user profile across different computers.

C:\System Volume Information

Contains system restore points and other system metadata.

C:\$Recycle.Bin

Stores deleted files and folders before they are permanently removed. Each user has a subfolder for their recycled items.

C:\Boot

Contains boot configuration data and files needed for the boot process.

C:\Pagefile.sys

A hidden system file used for virtual memory (paging file).

C:\Hiberfil.sys

 A hidden system file used for storing the contents of memory when the system hibernates.

C:\Swapfile.sys

A hidden system file used for modern app paging operations.

Linux Hierarchical Structure

The hierarchy of a Linux computer is structured in layers, each serving a specific purpose in managing hardware, software, and user interactions. Here’s an overview of the Linux hierarchy:

Hardware: The physical components of the computer, such as the CPU, memory, storage devices, and peripheral devices (keyboard, mouse, printer, etc.).

Firmware: Low-level software embedded in hardware components, such as BIOS or UEFI, which initialize hardware during the boot process.

Kernel: The core part of the Linux operating system that manages system resources, including memory management, process management, and hardware communication. The kernel operates in two modes:

  • Kernel Mode: Executes privileged instructions directly interacting with hardware.

  • User Mode: Executes user applications with restricted access to hardware.

Init System: Responsible for initializing the system and managing services and processes. Common init systems include:

  • Systemd: A widely used init system that provides parallel startup of services, on-demand starting of daemons, and other advanced features.

  • SysVinit: An older init system that uses a series of scripts to start and stop services.

  • Upstart: An event-based init system used in some distributions.

System Services (Daemons): Background processes that perform essential functions such as networking, logging, and system monitoring. Examples include sshd for SSH access and cron for scheduled tasks.

Shell: A command-line interface that allows users to interact with the operating system by executing commands. Common shells include:

  • Bash: The Bourne Again Shell, a popular default shell.

  • Zsh: Z Shell, known for its features and user-friendly enhancements.

  • Fish: Friendly Interactive Shell, designed for user-friendliness.

User Applications: Programs installed and run by users, such as web browsers, office suites, and text editors. These run in user mode and interact with the kernel and other system components through system calls and the API.

File System: Manages the storage, retrieval, and organization of files on storage devices. The root directory / is the starting point of the Linux file system hierarchy, with standard directories such as:

  • /bin: Essential binary executables.

  • /etc: Configuration files.

  • /home: User home directories.

  • /var: Variable files like logs and databases.

  • /usr: User-installed software and libraries.

Package Management System: Tools and utilities for installing, updating, and managing software packages. Common package managers include:

  • APT (Advanced Package Tool): Used in Debian-based distributions like Ubuntu.

  • YUM/DNF: Used in Red Hat-based distributions like Fedora and CentOS.

  • Pacman: Used in Arch Linux.

User Interface (UI): The graphical interface that allows users to interact with the computer. This includes:

  • Desktop Environments: Such as GNOME, KDE, XFCE, and others, providing a cohesive graphical user interface.

  • Window Managers: Such as Openbox, i3, and others, managing the placement and appearance of windows.

Security: Measures and components designed to protect the system and user data, including user accounts, permissions, SELinux (Security-Enhanced Linux), AppArmor, and firewall settings.

Networking: Tools and utilities to manage network connections and configurations, including network interfaces, routing, DNS, and services like NetworkManager or systemd-networkd.

macOS Hierarchical Structure

The hierarchy of a macOS computer is structured similarly to other operating systems but with specific components and frameworks unique to macOS. Here’s an overview of the macOS hierarchy:

Hardware: The physical components of the computer, such as the CPU, memory, storage devices, and peripheral devices (keyboard, mouse, printer, etc.).

Firmware: Low-level software embedded in hardware components, such as EFI (Extensible Firmware Interface), which initializes hardware during the boot process.

Kernel (XNU): The core part of the macOS operating system that manages system resources. XNU (X is Not Unix) is a hybrid kernel combining elements of the Mach kernel and components from BSD (Berkeley Software Distribution).

Drivers: Software that allows the operating system to communicate with hardware devices. These are known as kernel extensions (kexts) in macOS.

System Services (Daemons): Background processes that perform essential functions such as networking, logging, and system monitoring. Examples include launchd for service management and syslogd for logging.

Core OS: This layer includes the essential system libraries and frameworks that provide fundamental services:

  • Core Foundation: A low-level framework for managing data types and collections.

  • Core Services: Provides essential services such as file access, networking, and threading.

  • Kernel Extensions (kexts): Modules that extend the kernel's capabilities.

Frameworks: Higher-level services and APIs for developing applications:

  • Cocoa: The primary framework for developing macOS applications, based on the Objective-C runtime.

  • Carbon: An older framework for compatibility with applications from earlier versions of macOS (deprecated in modern macOS versions).

  • Metal: A framework for high-performance graphics and computation.

  • Core Animation: A framework for creating animated user interfaces.

User Interface (UI): The graphical interface that allows users to interact with the computer. This includes:

  • Aqua: The graphical user interface (GUI) of macOS.

  • Finder: The file manager and desktop interface.

  • Dock: The application launcher and switcher.

  • Menu Bar: The top bar that provides access to system menus and status indicators.

Applications: Programs installed and run by users, such as Safari (web browser), Mail (email client), and various third-party applications. These run in user mode and interact with the kernel and other system components through system calls and APIs.

File System: Manages the storage, retrieval, and organization of files on storage devices. The primary file system is APFS (Apple File System), with HFS+ used on older systems. The file system hierarchy includes:

  • /Applications: Contains installed applications.

  • /System: Contains system files and libraries.

  • /Library: Contains system-wide resources and configurations.

  • /Users: Contains user home directories.

  • /Volumes: Mount point for additional storage devices.

Package Management and Updates: Tools and utilities for installing, updating, and managing software packages. The Mac App Store and brew (Homebrew) are common sources for software management.

Security: Measures and components designed to protect the system and user data, including:

  • Gatekeeper: Controls the execution of downloaded applications.

  • System Integrity Protection (SIP): Prevents modification of critical system files.

  • FileVault: Provides full-disk encryption.

  • Sandboxing: Isolates applications to limit their access to system resources.

Networking: Tools and utilities to manage network connections and configurations, including network interfaces, routing, DNS, and services like System Preferences > Network.