What does the 'b' character do in front of a string literal?

Question

Apparently, the following is the valid syntax:

my_string = b\'The string\'

I would like to know:

1. What does this b

Answer 1

It turns it into a bytes literal (or str in 2.x), and is valid for 2.6+.

The r prefix causes backslashes to be "uninterpreted" (not ignored, and the difference does matter).