Strings ("string literals", to be precise) are enclosed in quotes (single or double).
Multi-line strings are enclosed in triple-quotes.
'x'
"Hello, world"
"""Twas brillig and the slithy toves
did gyre and gimble in the wabe."""
Values can be written into a string with the % operator:
>>> x = 1
>>> y = 2
>>> 'x = %d, y = %f' % (x,y)
'x = 1, y = 2.000000'