Apa itu "Taken for granted"?

Dear All,
I have some words that I don't understand the meaning. So, everyone please
help me by explaining these idiom :
"Taken for granted..."
Regards, Suhendra.

Free-English-Course@yahoogroups.com answer :

Taking for granted is not appreciating something or someone for what they are there for, have to offer, and can do. For instance, suppose you had a friend that you shared a class with and usually copied answers from. Then next term you find out she doesn't share any classes with you. You took her for granted that she'd always be around for you to copy from her, and now you can't.