The Python Apprentice

str – an immutable sequence of Unicode code points

Strings in Python have the datatype str and we've been using them extensively already. A string is a sequence of Unicode code-points, and for the most part you can think of code-points as being like characters, although they aren't strictly equivalent. The sequence of code-points in a Python string is immutable, so once you've constructed a string, you can't modify its contents.

The difference between code points, letters, characters, and glyphs can be confusing. Let's try to clarify with an example: The Greek capital letter Σ (sigma), which is of course used widely in the writing of Greek text, is also used by mathematicians to signify summation of a series. These two uses of the letter ...