String : 'hello'- sequence of character- immutableerror : s[i] = 'x'- s[i] : i th character in s List : ['alpha', 23]- list of elements- mutable- p[i] : i th element of p Dictionary : { 'hydrogen':1 , 'helium' : 23 }- set of pairs- mutable- d[k] : k : keyvalue associated with k in d