10) Early Access
When iOS 8 was released it came in a bulk and had lot of bugs. So company released lot of fixes which sometimes did more bad then good.
Hence this year with iOS 9 they have decided to release beta version of iOS 9 which is accessible by everyone including consumers and developers. As many might think that beta already has many bugs and will require crazy fixes but in fact, Apple has done it for the purpose.
Apple from its experience with iOS 8 decided that they'll first test iOS 9 with beta release and collect data from the user ( 1 million approx beta users) and fix all the bugs before the Full version release of iOS 9.