What is the difference between class and instance variables?

What is the difference between class and instance variables?

Class variables are shared among all instances of a class, while instance variables are unique to each instance.

Can you give me an example of each?

Sure! In Python, a class variable is defined within the class but outside any methods, while an instance variable is defined within a method using 'self'.

How do they affect memory usage?

Class variables use less memory since they are shared, while instance variables consume more memory as each instance has its own copy.

When should I use class variables instead of instance variables?

Use class variables when you want to store data that should be consistent across all instances, like a constant value.