literals are written using single or double quotesit doesn' matter which as long as the same kind of quote is used at both ends we can convert between strings and integersfor exampleint(" "and str( if an integer conversion fails valueerror exception is raisedwhereas almost anything can be converted to string strings are sequencesso those functions and operations that can be used with sequences can be used with strings for examplewe can access particular character using the item access operator ([])concatenate strings using +and append one string to another using +since strings are immutablebehind the scenesappending creates new string that is the concatenation of the given stringsand rebinds the left-hand string object reference to the resultant string we can also iterate over string character by character using for in loop and we can use the built-in len(function to report how many characters are in string for immutable objects like stringsintegersand tupleswe can write our code as though an object reference is variablethat isas though an object reference is the object it refers to we can also do this for mutable objectsalthough any change made to mutable object will affect all occurrences of the object ( all object references to the object)we will cover this issue in python provides several built-in collection data types and has some others in its standard library we learned about the list and tuple typesand in particular how to create tuples and lists from literalsfor exampleeven [ listslike everything else in pythonare objectsso we can call methods on them--for exampleeven append( will add an extra item to the list like stringslists and tuples are sequencesso we can iterate over them item by item using for in loopand find out how many items they have using len(we can also retrieve particular item in list or tuple using the item access operator ([])concatenate two lists or tuples using +and append one to another using +if we want to append single item to list we must either use list append(or use +with the item made into single-item list--for exampleeven +[ since lists are mutablewe can use [to change individual itemsfor exampleeven[ the fast is and is not identity operators can be used to check whether two object references refer to the same thing--this is particularly useful when checking against the unique built-in none object all the usual comparison operators are available (=>)but they can be used only with compatible data typesand then only if the operations are supported the data types we have seen so far--intstrlistand tuple--all support the complete set of comparison operators comparing incompatible typesfor examplecomparing an int with str or listwill quite sensibly produce typeerror exception python supports the standard logical operators andorand not both and and or are short-circuit operators that return the operand that determined their