macOS is the operating system that runs Apple computers

macOS is the software that controls how your Mac works — the system that starts when you turn it on, manages your files, runs your programs, and handles everything from your keyboard to your internet connection. It is made by Apple and comes built into every Mac computer. You cannot buy a Mac without it, and you cannot replace it with Windows or Linux the way you might on other computers.

Every few years, Apple releases a new version of macOS with a new name. Recent versions are called Sonoma, Ventura, and Monterey. Your Mac came with one version installed, and you can update to newer versions if your hardware is recent enough. Older Macs cannot run the newest versions — Apple stops supporting them after a certain point.

The main reason to understand macOS is that it works differently from Windows. If you are switching from a PC, or if you are helping someone who uses a Mac, knowing how macOS organizes things and where to find settings will save you hours of frustration.

Key Takeaways

  • macOS is Apple's operating system, built into every Mac, and you cannot replace it with another system the way you can on Windows computers.
  • Apple releases a new version of macOS every year with a new name, and older Macs cannot run the newest versions.
  • The Mac menu bar sits at the top of the screen and works differently from the Windows taskbar — clicking the Apple logo in the top-left corner opens system settings and shut-down options.
  • Files on a Mac are organized in Finder, which works like Windows Explorer but uses different names for folders and has different keyboard shortcuts.
  • macOS comes with built-in programs like Mail, Safari, and Notes that are free and cannot be uninstalled, though you can hide them.

The menu bar and how to find settings on a Mac

The menu bar is the thin strip at the very top of your Mac screen. It always stays there, even when you open programs. On the far left is the Apple logo — clicking it opens a menu with options to restart, shut down, sleep, or log out. This is where you go to turn off your Mac, not through a button on the case.

To the right of the Apple logo are menus for whatever program is currently open. If you are in Safari, you see Safari menus. If you are in Mail, you see Mail menus. On the far right side of the menu bar are small icons called menu extras — these show your Wi-Fi status, battery level, volume, and the time. Clicking any of these icons opens a small menu with quick settings.

System settings on a Mac are found in System Settings (or System Preferences on older versions). Click the Apple logo, then look for "System Settings" in the menu that appears. This is where you change your password, set up Wi-Fi, adjust display brightness, manage user accounts, and control almost everything about how your Mac behaves. It is organized into categories on the left side — click a category to see options on the right.

Finder and how files are organized

Finder is the program that shows you your files and folders on a Mac. It is the equivalent of Windows Explorer. You open Finder by clicking the blue smiling face icon in the dock (the row of icons at the bottom of your screen), or by pressing Command+Space and typing "Finder".

Finder shows your files organized into folders. The main folders you will see are Desktop, Documents, Downloads, and Applications. The Downloads folder is where files you read from the internet land automatically. The Applications folder holds all your programs. Unlike Windows, you do not install programs by running an installer — you usually just drag the program icon into the Applications folder, or read it from the App Store.

One confusing difference from Windows: on a Mac, a program icon in the Applications folder is the entire program. You do not need to look for a separate uninstaller. To remove a program, you drag it to the Trash. To back up your files, you can drag them to an external hard drive the same way.

The dock and launching programs

The dock is the row of icons at the bottom of your screen (or side, if you have moved it). It is a quick launcher for programs you use often. When you open a program, its icon appears in the dock while it is running. When you close the program, the icon stays there unless you remove it.

To add a program to the dock, open Finder, go to Applications, find the program you want, and drag its icon down to the dock. To remove it, right-click the icon in the dock and select "Remove from Dock". The program itself is not deleted — it just stops appearing in the dock.

The dock also shows open windows. If you have multiple windows open in the same program, you can click and hold on the dock icon to see a list of them. This is useful when you have many browser tabs or documents open and need to switch between them quickly.

Built-in programs that come with macOS

Every Mac comes with a set of programs already installed. These include Safari (the web browser), Mail (for email), Messages (for texting), Notes (for writing), Calendar, Reminders, Maps, and many others. These programs are free and cannot be uninstalled — they are part of macOS itself.

You do not have to use them. If you prefer Chrome over Safari, or Gmail over Mail, you can read those programs and use them instead. The built-in programs will still be there, but you can hide them from view by removing them from the dock and Launchpad (the grid of app icons you open by pressing F4 or clicking the grid icon in the dock).

One useful built-in program is Spotlight, which searches your entire Mac. Press Command+Space to open it, type what you are looking for, and Spotlight finds files, programs, and settings. This is faster than digging through folders.

Updates and security on macOS

Apple regularly releases updates to macOS. These updates fix security problems, add new features, and improve performance. Your Mac will notify you when an update is available. You can install it by clicking the notification, or by going to System Settings, clicking "General" on the left, and then "Software Update".

Updates usually require a restart. It is a good idea to install them when you have time, because they often fix security holes that hackers could use to access your computer. You can set your Mac to install updates automatically at night if you want — this option is in System Settings under General > Software Update.

macOS also comes with built-in security features like Gatekeeper (which checks programs before you run them) and FileVault (which encrypts your hard drive). These run in the background and you do not need to do anything to use them, though you can adjust their settings in System Settings under Security & Privacy.

Keyboard shortcuts that work differently on a Mac

If you are coming from Windows, the biggest difference is that Mac uses Command (⌘) instead of Control. On Windows you press Ctrl+C to copy — on a Mac you press Command+C. On Windows you press Ctrl+Z to undo — on a Mac you press Command+Z. This one change affects almost every keyboard shortcut you know.

Here are the most common ones: Command+C (copy), Command+V (paste), Command+X (cut), Command+Z (undo), Command+A (select all), Command+S (save), Command+Q (quit a program), Command+Tab (switch between open programs), and Command+Space (open Spotlight search). Learning these will make using a Mac much faster.

One more useful shortcut: Command+Delete moves a file to the Trash. To permanently delete it, you have to empty the Trash — right-click the Trash icon in the dock and select "Empty Trash". Until you do that, deleted files can be recovered.

Frequently Asked Questions

Can I run Windows programs on a Mac?

Not directly. Some programs have Mac versions you can read. For others, you can use virtualization software like Parallels Desktop or VMware Fusion, which runs Windows inside macOS. This requires buying Windows separately and takes up disk space, so it is only worth it if you really need a specific Windows program.

What is the difference between macOS and iOS?

iOS is the operating system on iPhones and iPads. macOS is the operating system on Mac computers. They are related and share some features, but they are separate systems. You cannot run iPhone apps on a Mac, though some developers make versions of their apps for both.

How do I know what version of macOS I have?

Click the Apple logo in the top-left corner, then select "About This Mac". The window that opens shows your macOS version at the top. You can also see how much storage you have left, how much memory (RAM) your Mac has, and other hardware details.

What should I do if my Mac is running slowly?

First, restart it — this clears temporary files and stops programs that are using memory. If it is still slow, open Activity Monitor (press Command+Space, type "Activity Monitor", and press Enter) to see which programs are using the most resources. You can also check how much free storage you have left — Macs slow down when the hard drive is almost full.

Is macOS safer than Windows?

macOS has some built-in security features that Windows does not, and viruses designed for Windows cannot run on a Mac. However, Macs can still be infected with malware designed for macOS. The safest approach on any computer is to keep your software updated, use strong passwords, and be careful about what you read.