Full screen or maximize? What the green button does on a Mac

A Mac has three ways to make a window bigger, and only one of them takes it off your desktop. Full screen moves the window into a space of its own. Fill and Zoom leave it where it is, next to your other windows, with the menu bar and Dock in view. This is how each works on macOS 14 Sonoma through macOS 27, and how to reach each from the keyboard.

The green button

The green button is the third of the three buttons in a window's top-left corner. Click it and the window goes full screen: the app fills the entire display, the menu bar and Dock hide until you move the pointer to them, and macOS gives the app a space of its own, next to your desktops in Mission Control. That's the same on every version from macOS 14 to macOS 27 (Apple's full-screen guide).

Hold the pointer over the button without clicking and a menu appears instead. What's in it depends on your macOS:

Apple's own advice is in the same guide: to work in a bigger window without going full screen, maximize the window instead, and the menu bar and Dock stay visible. On a Mac, maximizing comes in two kinds, Zoom and Fill, and they don't do quite the same thing.

Zoom

Zoom is the older of the two and is in every version of macOS. It switches a window between two sizes: the size you gave it, and a size the app picks as the best fit for what the window shows. Apple's developer documentation gives a word-processing window as the example: its best width is the width of a page or of the display, whichever is smaller. An app that doesn't choose gets a size that nearly fills the screen (AppKit documentation).

So Zoom filling the screen in one app and only widening a window to fit its contents in another isn't a bug: the app decides. Three ways to zoom:

• Window › Zoom in the menu bar, in apps such as Finder, Safari, Chrome and Terminal. Choose it again to go back.
• ⌥-click the green button. On macOS 14 this is Apple's way to maximize a window, and ⌥-clicking again returns it to its previous size. Apple's guides for macOS 15 and later describe Fill for maximizing, and keep ⌥-clicking the green button as the way back to the previous size (Move and arrange app windows).
• Double-click the title bar, once the setting below is set to Zoom.

Zoom has no keyboard shortcut in Apple's lists. If you want one, add it yourself: in System Settings › Keyboard › Keyboard Shortcuts › App Shortcuts, click the add button, choose All Applications, type Zoom as the menu title, and press the keys you want (Apple's guide to app shortcuts). Pick keys no other shortcut uses, or the new one won't work.

Fill

Fill came with window tiling in macOS 15 Sequoia. It makes the window fill the desktop: the space between the menu bar and the Dock, or below the menu bar and beside the Dock if yours is on the side. Unlike Zoom, it doesn't ask the app what size it would like. Four ways to fill:

• Hold the pointer over the green button, then click the Fill layout under Fill & Arrange.
• Choose Window › Fill.
• Press Fn-⌃F. On newer keyboards Fn is the Globe key.
• Drag the window by its title bar up to the menu bar, while Drag windows to menu bar to fill screen is on in Desktop & Dock settings.

The Fn-⌃ keys come from Apple's list of window tiling shortcuts, and ⌃⌘F from Mac keyboard shortcuts. macOS 14 has no Fill. There, use Zoom, or set the title-bar double-click to Zoom. Apple's macOS 14 guide says Zoom expands a window to fill the space between the Dock and the menu bar, though each app can still pick a smaller best size. Fill is one of a whole set of layouts; the halves, quarters and multi-window arrangements are in how to tile windows on a Mac.

Double-click the title bar

Double-clicking a window's title bar can fill the desktop, zoom the window, minimize it, or do nothing. You choose in System Settings › Desktop & Dock, in the Dock section. The setting's name and choices depend on your macOS (Desktop & Dock settings):

On macOS 15 and later, choose Fill if you want a double-click to make every window as big as the desktop, and Zoom if you'd rather each app pick its own best size. On macOS 14, Apple describes Zoom as filling the space between the menu bar and the Dock, though, as above, each app can pick a smaller best size.

Enter and leave full screen

Any of these puts the front window in full screen:

• Click the green button.
• Press ⌃⌘F, in apps that support it.
• Hold the pointer over the green button and choose Full Screen › Entire Screen on macOS 15 and later, or Enter Full Screen on macOS 14.
• Choose View › Enter Full Screen in apps that have it, such as Finder, Safari, Chrome and Terminal.

And any of these brings it back to your desktop:

• Press ⌃⌘F again.
• Move the pointer to the top of the screen so the menu bar and the window's title bar show, hold the pointer over the green button, and choose Exit Full Screen.
• Open Mission Control, hold the pointer over the app's thumbnail in the Spaces bar, and click the Exit button that appears. This ends Split View too (Apple's guide to spaces).
• In Google Chrome, press Fn-F or hold down Esc, according to Chrome's list of shortcuts.

While an app is in full screen, you move between it and your desktops like any other space: ⌃← and ⌃→, a swipe with three or four fingers, or Mission Control. The details are in how to switch between full-screen apps.

Which one to use

Full screen suits one task with nothing else in view: writing, a video, a presentation, or making the most of a laptop's screen. The cost is that the app is now in another space, so getting to your other windows means changing space. For two apps side by side in full screen, see Split View.

Fill suits a big window you switch to and from all day. It stays on your desktop with everything else, so ⌘Tab, the Dock and your other windows work as usual, and Fn-⌃R undoes it.

Zoom suits apps that know their best size, such as a document that reads best at page width, and it's the way to maximize on macOS 14.

With Flick

Flick is a window switcher, so it doesn't resize anything: there's no Fill or Zoom in it. What it does is take you to a window wherever it is. Full-screen windows are in Flick's list next to all the others, marked with a Full Screen icon, so you can go from a filled window on your desktop to a full-screen app and back without counting spaces. Hold ⌥ and tap Tab, or type part of the app's name or the window's title, then let go: Flick switches to that window's space.

If you turn on Show only the active Space in Flick's settings (it's off by default), each full-screen app counts as a space of its own, so its window drops out of the list until you're in it. Flick needs macOS 14 or later, and the free version switches between your 5 most recent windows. More in Spaces, minimized and hidden windows.

See how Flick handles Spaces and full screen