Python allows you to put underscores in numbers for convenience. They're used to separate groups of numbers, much like commas do in non-programming. Underscores are completely ignored in numbers, much like comments. So this:
x = 1_000_000
is interpreted to be the same as this:
x = 1000000
However, you can't put two underscores right next to each other like this:
x = 1__000__000 #SyntaxError
