The only IDE for Android App Development was Eclipse, with the ADT [Android Development Tools] plugin provides in the "Android SDK" [Software Development Kit]. But, it was laggy as hell, gave too many unpredictable errors and was quite difficult to handle for budding developers.
|Eclipse with the ADT plugin|
For now, Android Studio is just a "Preview Access" and has some bugs, but in the distant future, it WILL be the main IDE for Android App Development.
You may experience some problems while setting-up Android Studio. But don't worry, just refer to this excellent post on XDA-Developers forum by user "lolrenx" [Link].