is figure gives more accurate picture of the effect of assignment in python an arrow is used to show which value variable refers to notice that the old value doesn' get erased by the new onethe variable simply switches to refer to the new value the effect is like moving the sticky note from one object to another this is the way assignment actually works in pythonso you'll see some of these sticky-note style pictures sprinkled throughout the book as well before after figure variable as sticky note (pythonview of by the wayeven though the assignment statement doesn' directly cause the old value of variable to be erased and overwrittenyou don' have to worry about computer memory getting filled up with the "discardedvalues when value is no longer referred to by any variableit is no longer useful python will automatically clear these values out of memory so that the space can be used for new values this is like going through your closet and tossing out anything that doesn' have sticky note to label it in factthis process of automatic memory management is actually called garbage collection assigning input the purpose of an input statement is to get some information from the user of program and store it into variable some programming languages have special statement to do this in pythoninput is accomplished using an assignment statement combined with built-in function called input the exact form of an input statement depends on what type of data you are trying to get from the user for textual inputthe statement will look like thisinput(here is string expression that is used to prompt the user for inputthe prompt is almost always string literal ( some text inside of quotation markswhen python encounters call to inputit prints the prompt on the screen python then pauses and waits for the user to type some text and press the key whatever the user types is then stored as string consider this simple interactionname input("enter your name"