Is it compulsory to insert all the curly brackets in a piece of code. And why. And when

Answer 1

With curly brackets and think that is code more readable...

Answer 2

Codes have to be converted to 0 and 1's for the computer to understand it,curly brackets tell the computer that that is particular block of code.In Python indentation is used.Without these the computer will be messed not knowing what to process or where to start