When is initialization needed? When is it not needed?

What will be an ideal response?

Initialization is needed when a variable in an expression about to be evaluated has not yet been assigned a value. This must be done for variables in conditional expressions (in IF and LOOP statements) as well as for variables in arithmetic expressions. This includes all variables on the right of the equal sign in a LET statement.
Initialization is not needed when a value in an expression has been previously assigned by:
A LET statement (for example by a calculation)
An INPUT statement.
Remember, variables on the left of the equal sign in a LET statement do not need to be initialized before hand. In fact this is how they get initialized.