Facebook API "This app is in development mode"

Question

What does "development mode" mean for a facebook app? I find no exact explanation of what I can and can't do while in development mode and what's the relation with the "Not available to all users because your app is not live".

Some people also refer to it as "Sandbox mode" so I have a lot of confusion between "development mode", "sandbox mode", "live vs not available to general public"

Answer 1

I know its a little bit late but someone may find this useful in future.

STEP 1:

Login to facebook Developer -> Your App

In Settings -> Basic -> Contact Email. (Give any email)

STEP 2:

And in 'App Review' Tab : change

Do you want to make this app and all its live features available to the general public? Yes

And you app will be live now ..