6.87 How to use MapThread to map function on 2 lists?

Given lists a={1,2,3}, b={4,5,6} and we want to do operation from slot 1 from a with slot 1 from b, and so on. For this, we can use ‘MapThread‘. Suppose we want to add each corresponding slot, then

a = {1, 2, 3} 
b = {4, 5, 6} 
MapThread[(#1 + #2) &, {a, b}] 
 
   (*  {5, 7, 9} *)
 

Of course, in this simple example, doing a+b will work, but this is just an example.