You'll often hear us ask you which is broken - the glass, the LCD, or both. For iPad, iPhones, Macbooks.. let me explain how this works.
The iPad has a glass touchscreen that you touch. This is the part that is exposed, and most often breaks.
The iPad has an LCD screen that makes the picture. This is a separate part in some cases.
A1278, A1286, and A1297 Unibody Macbook Pros, if purchased with a glossy display, have a glass and an LCD as well.
Unlike on the iPhone or iPad, the glass serves no purpose. It is not part of a touchscreen, it is just... there. Why? You got me - I think the A1342 White Unibody Macbook screen looks MUCH Better as a result of not having the glass over it. Ask Apple on that one.
If you can see the picture clearly - nothing is missing, distorted, or bleeding, the LCD is fine. If the picture has lines running through it, or is bleeding, or missing sections, the LCD is bad.
If you can see the picture just fine but it looks like you are looking at a TV screen through a cracked house window, the LCD is fine, but the glass is broken.
If you have any questions as to which is bad, feel free to ask us, send us pictures, or come to the store. Some items have different prices depending on whether the glass or LCD are broken - such as the Unibody Macbook Pros from 2008-2012, the iPad 2, 3, 4 ,and mini. Some like the iPhone 5, cost the same regardless of which are broken.
We'll always be happy to help.