I recently got a chance to use a macOS laptop from my friend. He had just bought it and honestly had almost no idea how macOS worked. I had a little bit of knowledge about it, so naturally I became the “tech support guy.”
One day we tried installing an app.
I opened YouTube, watched 2–3 tutorials, and every video showed the exact same thing:
“Just drag the app into the Applications folder.”
That was it.
No installer.
No next-next-finish wizard.
No loading bars.
No “accept terms and conditions.”
Nothing.
At first it felt strange.
As someone who used Windows for years, my brain was expecting an .exe installer, registry updates, shortcuts, setup screens, and maybe even a forced restart.
But on macOS?
You drag an icon into a folder and suddenly the application is installed.
That made me curious.
Why is installing apps on macOS so simple?
And why does Windows need installers for almost everything?
So I started digging deeper, and what I found was surprisingly interesting.
The First Weird Discovery
On macOS, applications usually end with .app.
At first, I thought .app in macOS was equivalent to .exe in Windows.
Turns out that assumption is completely wrong.
I opened the Applications folder from the terminal and listed its contents.
Everything looked normal at first:
Firefox.app
Safari.app
Discord.app
These looked like executable files.
But when I checked their actual file type, something unexpected appeared.
They were not files.
They were directories.
Folders.
That completely changed my understanding.
Finder, the macOS file manager, visually shows applications like single executable objects. But internally, they are actually structured folders containing many files.
In simple words:
A macOS app is basically a special folder pretending to be a single application.
Why Double-Clicking Works in Finder But Not in Terminal
Here’s where things become interesting.
If you double-click Firefox in Finder, the browser launches normally.
But if you try running Firefox.app directly from the terminal like an executable, it fails.
Why?
Because the terminal and the kernel see reality differently than Finder does.
The kernel only sees a directory.
And directories cannot be executed as programs.
This confusion happens because Finder abstracts the complexity away from users.
Finder says:
“Hey, this folder should behave like an application.”
The terminal says:
“That’s literally just a folder.”
And technically, the terminal is correct.
What Actually Happens When a Program Launches
In Unix-like systems such as macOS and Linux, launching a program usually involves system calls like:
fork()execve()
The operating system creates a process and then replaces it with the executable program.
But here’s the problem:
Firefox.app itself is not the executable.
It is only a container.
The real executable binary exists somewhere inside that folder.
So when the terminal tries to execute the .app path directly, the kernel refuses because it received a directory instead of a binary executable file.
That’s why macOS provides the open command.
When you run:
open Firefox.app
macOS internally checks the application bundle, finds the real executable, and launches it properly.
The Idea of Application Bundles
At this point, another question appeared in my head.
If applications are just executable files, why not simply keep all executables in one folder?
Because modern applications are much bigger than a single binary.
A real desktop application usually contains:
- Icons
- Images
- Fonts
- Configuration files
- Dynamic libraries
- Plugins
- Localization files
- Frameworks
- Assets
All these resources are necessary for the application to function properly.
macOS solves this problem using something called an Application Bundle.
Instead of scattering dozens of files across the system, macOS groups everything into a single structured folder with the .app extension.
To the user, it looks like one app.
Internally, it is an organized package.
Honestly, this is a very elegant design.
Finder Is Not the Kernel
One of the most important things I learned during this exploration was this:
The kernel is not responsible for how applications look in the graphical interface.
That responsibility belongs to user-space programs like:
- Finder
- Desktop environments
- File managers
The kernel only provides access to the filesystem.
The graphical layer decides how things should appear to humans.
That means Finder intentionally hides complexity.
It sees a .app directory and says:
“I will display this as a beautiful application icon instead of a normal folder.”
This is why macOS feels polished.
A lot of complexity is hidden behind abstractions.
What Exists Inside a macOS App?
Once I discovered .app files were folders, I wanted to see what was actually inside them.
macOS allows this through:
“Show Package Contents”
And suddenly the illusion disappears.
Inside a typical app bundle, you usually find something like this:
MyApp.app
└── Contents
├── MacOS
├── Resources
├── Frameworks
└── Info.plist
Each folder has a specific purpose.
MacOS
Contains the actual executable binary.
Resources
Contains icons, images, assets, localization files, and UI resources.
Frameworks
Contains dependencies and libraries the app needs.
Info.plist
This is the most important file.
It tells macOS things like:
- Application name
- Executable location
- App icon
- Version information
- Supported file types
- Permissions
- Capabilities
In many ways, Info.plist acts like the identity card of the application.
Finder reads this file to understand how the application should behave.
Why Windows Uses Installers
Then I compared this behavior with Windows.
On Windows, applications are usually stored inside:
Program FilesProgram Files (x86)
But unlike macOS, Windows does not treat application folders as special bundles.
Instead, Windows relies heavily on executable files (.exe) and something extremely important called the Windows Registry.
The registry is basically a massive centralized database that stores information about installed applications.
Things like:
- File associations
- Default programs
- Start menu integration
- Uninstall information
- Application paths
- Context menu actions
This is why Windows installers exist.
The installer does more than just copying files.
It also:
- Updates the registry
- Creates shortcuts
- Registers file types
- Integrates the app into the operating system
Without these setup steps, Windows would not fully recognize the application.
So in Windows, installation is not only about placing files somewhere.
It is about integrating the app into the entire operating system.
The Interesting Difference
This is where the real philosophical difference appears.
macOS bundles most application metadata inside the application itself.
Windows stores much of that information separately in the registry.
macOS says:
“The app carries its own identity.”
Windows says:
“The system keeps track of the app.”
Neither design is necessarily wrong.
They are simply different approaches.
What About Linux?
Linux becomes even more interesting.
Linux itself is only a kernel.
Different Linux distributions combine that kernel with different desktop environments, package managers, and user-space utilities.
Because of that, Linux does not have one universal installation method.
Some systems use:
.deb.rpm- Flatpak
- Snap
- AppImage
Different desktop environments also handle applications differently.
However, many Linux systems follow shared standards like the XDG Desktop Entry Specification to improve compatibility between environments.
But compared to macOS and Windows, Linux gives much more flexibility — and sometimes much more chaos.
The Real Reason macOS Installation Feels Magical
After understanding all this, the “drag and drop installation” no longer felt magical.
It finally made sense.
When you drag an app into the Applications folder on macOS, you are not installing a tiny executable.
You are moving an entire self-contained application bundle.
Everything the application needs already exists inside that package.
Finder simply understands how to interpret and launch it.
And honestly, once you understand the architecture behind it, the design feels incredibly smart.
What looked simple on the surface was actually hiding a beautifully engineered system underneath.
