Indexing and slicing

Each character in a string has a position called an index. Counting starts at 0.

 p  y  t  h  o  n
 0  1  2  3  4  5
-6 -5 -4 -3 -2 -1

word = "python"
print(word[0])    # p   first character
print(word[3])    # h
print(word[-1])   # n   negative index counts from the end

Slicing

word[start:end] gives the part from start up to, but not including, end.

print(word[0:3])   # pyt
print(word[2:])    # thon   (no end = till the end)
print(word[:2])    # py     (no start = from the beginning)
print(word[::-1])  # nohtyp (step -1 = reversed)