in this manner makes the assignment effective by copying only the referenceand not the datanum num figure variables with different values have different identifiers this statement num num links the variable num to new object stored at memory location number say having value as num is an integerwhich is an immutable typeit is rebuiltas shown in figure deciding usage of python data types it is preferred to use lists when we need simple iterable collection of data that may go for frequent modifications for exampleif we store the names of students of class in listthen it is easy to update the list when some new students join or some leave the course tuples are used when we do not need any change in the data for examplenames of months in year when we need uniqueness of elements and to avoid duplicacy it is preferable to use setsfor examplelist of artefacts in museum if our data is being constantly modified or we need fast lookup based on custom key or we need logical association between the key value pairit is advised to use dictionaries mobile phone book is good application of dictionary operators an operator is used to perform specific mathematical or logical operation on values the values that the operators work on are called operands for examplein the expression numthe value and the variable num are operands and the (plussign is an operator python supports several kinds of operators whose categorisation is briefly explained in this section - python compares strings lexicographicallyusing ascii value of the characters if the first character of both the strings are samethe second character is comparedand so on