While you may be tempted to minimize windows or move them around on your screen to view the windows behind them, that's almost never the fastest option.

To quickly move between open programs, leave the foremost window where it is and try one of the following methods:

Dock: Click the icon of the program you want to switch to in the Dock.

Cmd-Tab: Press and hold Cmd, press Tab one or more times to highlight the program you want to switch to, and then let go of both keys. If you press Tab too many times while still holding Cmd, you can press ` (tilde, the key above Tab), Shift-Tab, or the left-arrow key to move in the other direction. While the application switcher is showing (i.e., after pressing Tab once with Cmd held down), you can also select the desired program with the mouse. If you know the program you want to switch to was the most recently used program, you can press Cmd-Tab and immediately release both keys to switch to the other program without waiting for the application switcher to show, and then repeat this to switch back.

If you'd prefer not to have a program's window visible in the background, you can press Cmd-H to hide the program while still being able to switch to it with Cmd-Tab. For some programs, like Zotero, you can also close the main window without quitting the program and reopen it by using Cmd-Tab followed by Cmd-0 or by clicking the program's Dock icon. (If you minimize a window, it's no longer accessible via Cmd-Tab, though you can still open it via the Dock icon.)

Mission Control: If you only have a few windows open and are using a Mac with a trackpad, you can swipe up on the trackpad with four fingers to activate Mission Control, which displays all open windows, and then click on the window you want to switch to. (If this isn't working for you, check Trackpad settings in System Preferences.)

Taskbar: Click the icon of the program you want to switch to in the taskbar.

Alt-Tab: Press and hold Alt, press Tab one or more times to highlight the program you want to switch to, and then let go of both keys. If you press Tab too many times while still holding Alt, you can press Shift-Tab to move in the other direction. If you know the program you want to switch to was the most recently used program, you can press Alt-Tab and immediately release both keys to switch to the other program, and then repeat this to switch back.

Launcher: Click the icon of the program you want to switch to in the launcher.

Alt-Tab: Press and hold Alt, press Tab one or more times to highlight the program you want to switch to, and then let go of both keys. If you press Tab too many times while still holding Alt, you can press Shift-Tab to move in the other direction. If you know the program you want to switch to was the most recently used program, you can press Alt-Tab and immediately release both keys to switch to the other program without waiting for the application switcher to show, and then repeat this to switch back.