A short and sharp tip for today.
For a while now, Windows Phone has been capable of a form of multitasking allowing you to switching between applications without losing the state of an app. Apps had to be written to support this feature properly but most popular apps will have this baked in for Windows Phone 8 handsets.
Anyway, in order to use multitasking you just need to hold down the back button on the handset and your current app will shrink from full screen into a scrolling list allowing you to select another recently accessed application. However, apps will only appear if you use the Window key to exit them rather than quitting them with the back button – something worth remembering if you want to take advantage of this feature.