As mentioned previously, Windows 8 is designed to be part of an ecosystem, alongside Windows Phone and Windows RT. Microsoft believes in this idea so strongly that it has made the Windows 8 user interface (formerly called Metro) the primary interface for Windows users. PCs with the new OS installed will boot into the Windows 8 interface; the OS offers no built-in way to set it to boot to the traditional Windows desktop.
The Windows 8 interface acts as the Start menu now. Instead of appearing as columns of small icons that pop up when you click the Start button, all your applications show up as tiles on the Windows 8 Start screen. You can also search for an application by typing its name when you're in the Start screen; the results list autosorts as you type more characters.
It's important to realize that the Start screen is no more Windows 8 than the Start menu was Windows 7 or Windows XP. The screen exists as a launchpad for applications, not as a desktop replacement. That concept is easy to forget, since the Start screen occupies the entire display. Even so, Windows 8 apps consume the entire screen, whereas desktop applications can still run in a window on the desktop.
However, not all desktop applications appear on the Start screen by default. Some accessory apps, such as Paint, live in the Apps screen. You can force these programs to appear in the Start screen by right-clicking them to select them and then clicking Pin to Start at the bottom of the screen. Nevertheless, getting to the Apps screen is simple: Right-click a blank area in the Start screen and then click the All apps icon at the lower right.
This is where you'll run into a fundamental change in how you interact with Windows. Previously, right-clicking an object on the desktop always brought up a context menu, giving you a choice of actions to take. In the Windows 8 interface (but not the desktop), right-clicking now produces a bar at the bottom of the screen containing assorted context-sensitive items. It's a jarring change, but the arrangement makes sense within the context (no pun intended) of a touch-based display such as a tablet's. (Context-clicking still works the same way when you're in the Windows desktop.)