The range() and xrange() are built-in functions in Python that can be used to iterate over a sequence of values. While the range() function returns a sequence object, xrange() creates a generator-like object that yields the same values as range() but only keeps one number in memory at a time. xrange() is no longer used in Python 3, as the range() function now serves the same purpose. However, xrange() was used in earlier versions of Python and has a slightly different syntax. Both functions are used to generate a range of numbers to use in for loops.