Why is garbage collection important?
Lisp allocates storage as needed for your program’s data. You don’t have direct control over how or when storage is allocated; the compiler is free to do the best job it can to satisfy the meaning of your program. Lisp does not provide a way for your program to explicitly deallocate storage. This is an important feature, because you can never write a program to mistakenly deallocate storage that is still needed elsewhere in the program. This eliminates an entire class of errors, sometimes referred to as “dead pointer bugs” in languages that support explicit storage allocation and deallocation. On the other hand, your program may eventually run out of memory if your program never deallocates storage. So a language (like Lisp) that doesn’t support explicit deallocation must still provide a mechanism to automatically deallocate storage when the storage is no longer needed. The garbage collector’s job is to figure out which storage can no longer be accessed by your program, and then recycl
