Multitask between multiple applications

- [Narrator] The first computer that I ever had…was only able to run one application at a time.…Today, that idea seems crazy.…You will almost certainly need to run…multiple applications at the same time…and jump back and forth between them.…This is known as multitasking.…You've probably already heard me talk about…the active application.…No matter how many applications you have running,…only one application at a time is active.…It's usually the one where the window is at the top…of the stack, but you can always tell because…it's the application who's menus are visible…up at the top of the screen.…

But why is it so important for an application to be active?…Well, the act of application has your focus.…Usually there's a window that your interacting with…but if you need to access the menus, that application…needs to be active and if you do a keyboard command,…that command will trigger in the active application.…So right now I can see that calculator is my active…application and I can easily switch to another…application by clicking on that application's window.…