Python: what is the difference between (1,2,3) and [1,2,3], and when should I use each?

Question

In many places, (1,2,3) (a tuple) and [1,2,3] (a list) can be used interchangeably.

When should I use one or the other, and why?

Answer 1

a = (1,2,3) is a tuple which is immutable meaning you can't add anything into a b = [1,2,3] is a list in python which is immutable meaning you can make changes into 'b' either delete or add numbers into it.