Why C# local variables must be initialized?

Question

I am reading MCTS Self Paced Training Kit (70-536) Edition 2 and in the 1st chapter we have the following.

How to Declare a Value Type Variable To

Answer 1

Do make it Role of THUMB in C# and VB.net that before calling any variable, do initilize it first. like

int myInt; // Simple Declaration and have no value in it 
myInt= 32; // Now you can use it as there is some value in it..