x = (1, 2, 3)
x[0] # 1
x[1] # 2
x[2] # 3
x[3] # IndexError: tuple index out of range
Indexing with negative numbers will start from the last element as -1:
x[-1] # 3
x[-2] # 2
x[-3] # 1
x[-4] # IndexError: tuple index out of range
Indexing a range of elements
print(x[:-1]) # (1, 2)
print(x[-1:]) # (3,)
print(x[1:3]) # (2, 3)