Developer Option
As a user we are provided with the best settings options to have an optimal performance for our devices. But there are also several options (hidden or visible) which are meant for the use of developers only so that they can diagnose​ the system  and enhance the performance.
As user if we do not have any knowledge of these settings them playing with these options can lead our device in a trouble and can make our devices unstable to be used.
For android developer options:-
Go to settings->About phone->touch Build number seven times.
You will see an option namely developer options in the main settings list above the about device option.
For Windows:-
Got to settings -> Updates -> Developers options and select as per your use.