If you're on OS X, you use Mission Control with a trackpad or a mouse. I don't understand why everyone is talking about Cmd+Tab. I actually wrote a little app that puts Quit and Hide buttons in the top left and right corners of the screen. It's unfortunate that those commands were moved to a sub-menu in Mac OS X. In the old NeXTSTEP days, the Hide and Quit commands were top-level menu buttons and always just a single click away. When you return to the hidden app via Command+Tab, the app and its windows will be restored just as you left it. This will hide the active app and activate the next app in order. (Command+H, select 'Hide' from the app menu, or Option+Click a dock icon.) More often, you should use the Hide command. Typically, it's a rarely used command, but it can occasionally useful when you're working in an app that has a lot of windows open (like, say, Terminal) and you want to set some of the windows aside for awhile. You only use Minimize when you explicitly do not want to see a window when its app is active. Never use Minimize when you intend to switch between apps.

If you're having that problem then you're not using the Minimize command correctly.

and you don’t get your window, just the title in the menu bar! You might come across a situation, where you want to switch to an application or open a new instance of it.

Mac switch between windows of same app