SLEEP BUTTON AND HOME BUTTON
There are two main buttons on the iPad; the Sleep Button (top right-hand corner) and the Home Button (on the front) .
What is the difference you ask?
Press the Sleep Button to put your iPad into 'stand-by' mode. Podcasts and music will continue to play.
To turn your iPad off completely you need to hold the Sleep button down until a Slide to Power Off slider appears (about 4-5 seconds). Once you drag the button across your machine will completely turn off.
Turning off your machine is a good idea if you are not going to be using it for a while.
If your iPad is in 'Stand-by' (sleep) mode you can press the Home Button to wake it up. You can also use the Home Button to cycle between the Home Page and the Search screen (Spotlight Search).
Photo By Appsame (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons