What is len() function used for in list and tuple?

Question :

What is len() function used for in list and tuple?

With lists and tuples, len() function returns the number of elements in the sequence, For example,
>>> len ( [ 'a' , 'b', 'c', 'd', ] )
4
>>> len ( ( 2, 4, 6, 8, 10, 12 ) )
6