indentation blocking in Python

[ajetrumpet at gmail.com]

hello all,

This has got me a tad bit confused I think.  I am running 3.3.0 and I know that Python looks to group code together that is supposed to be in the same block.  But the question is, where are the rules for this?  For instance, if I type the following in a PY file, it errors out and I don't see the DOS window with the output in Vista:

a=1;
   if a==1: print(1)
   else: print(0)
wait = input("press key")

However, if I don't indent anything at all, it works!

a=1;
if a==1: print(1)
else: print(0)
wait = input("press key")

Can someone offer just a little explanation for this?  'IF' and 'ELSE' are obviously in the same code block.  Are they not?  Maybe it's not so obvious.  Thanks.