Finishing up the list of topics every unity developer should know

This thread will used to list down all the must known things by a Unity3D Developer !

This list could be from a experienced developer to new upcoming developers, could be from game designers to game developers, could be from companies looking for skills in theirs hires etc.

I hope this list could help new and experienced developers to weigh them and help them direct their work experience in all directions to help them balance the skills.