Sequences are those types that support Indexing and Slicing. In that respect, strings, unicodes, lists, tuples, buffers and xrange are all sequence types
Indexing allows you to fetch a particular item in the sequence directly
Slicing operation which allows us to retrieve a slice of the sequence i.e. a part of the sequence
For example:
t = 12345, 54321, ‘hello!’
>>> t
(12345, 54321, ‘hello!’)
>>> t[0]
12345
>>> t[:-1]
(12345, 54321)