By default, your iPad will automatically adjust its brightness thanks to a setting called Auto-Brightness (which can be turned off). Whether or not it is enabled, you can always manually dim the screen (lower brightness, well suited for reading in bed, for example), or make it brighter (ideal in a direct sunlight situation, which makes the iPad's screen harder to see). This tutorial explains how to manually decrease or increase the brightness of the display on your iPad, depending on where you are using it.
Follow these steps to change your screen brightness:
This is how you change the brightness of your iPad's screen using the global settings - some applications (like iBooks or the Kindle application for iPad) let you change the display brightness from the app itself, which spares you from having to stop what you are currently doing to go make your display brighter or dimmer. Keep in mind that a brighter display runs down your battery faster.
Tip: if you notice that your iPad increases or decreases the brightness of its display without your intervention, it means that the Auto-Brightness setting is turned on (it is by default). Learn how you can temporarily disable Auto-Brightness on your iPad (and re-enable it manually later on).