quotation marks - In Python what do the different quotes mean in this situation? -

i thought knew different types of python quotations mean, got little confused example:

my_string = 'the cat sat on mat'  my_string = "the cat sat on mat"  my_string = """the cat sat on mat"""  my_string = '''the cat sat on mat''' 

the first 2 seem 2 different ways of declaring string using single or double quotes. last 2 seem comments leave expressions incomplete (and generate error in interpreter. right?

the last 2 not comments , multi-line strings, if print out last 2 strings see output on console.

my_string3 = """the cat sat on mat"""  print my_string3 >>> cat sat on mat 

if """...""" denoted comment must have received error message while initializing such variable a = #dad raise error.

as strings initialized """ multi-line can initialize strings as:

my_string3 = """the cat sat on  mat"""   print my_string3 >>>     cat sat on      mat