free is just a way for you to tell the C runtime that you are done using a piece of memory and that it may be re-used to handle another malloc request. Of course, the programmer has to know that he is done with a particular piece of memory, and it can be very difficult to determine at what point that is the case. GC just removes the need to call free - some algorithm runs around and determines what memory you are done with, and returns it to the free store for you. In essence, GC allows you to operate under the illusion that you have unlimited memory.

[ignoring destructors/finalizers for now]