If you have ever used an Android device, you have probably noticed that it works quite differently to many other operating systems. For example, you can be using an app on your device, perhaps checking what people are doing on Facebook.
Then, you get an email notification and you tap the notification to read it. Halfway through reading the email, you might get a Twitter notification and, because you are waiting on important news from someone you follow, you interrupt your email reading and change apps to Twitter with a touch.
After reading the tweet, you fancy a game of Angry Birds; however, halfway through the first fling, you suddenly remember the Facebook post. So, you quit Angry Birds and tap on the Facebook icon.
You will likely resume Facebook at the exact same point that you left it. Afterward, you could then go back to reading the email, decide to reply to the tweet, or start an entirely new app.
