Are Stanford and MIT Ivy League schools?

Do Stanford and MIT belong to the Ivy League? I've heard conflicting information about this.

No, Stanford and MIT aren't a part of the Ivy League. They're just as competitive as Ivy League schools (or more so), but they don't officially belong to the group. The Ivy League consists of the following eight schools:

Brown
Columbia
Cornell
Dartmouth
Harvard
UPENN
Princeton
Yale