Where are objects stored in memory?

Objects in memory are usually stored in the heap.

The heap is a region of memory where objects are dynamically allocated during program execution. The lifetime of objects in the heap is determined by the garbage collector (if present in the language) or by explicit memory deallocation.

Unlike the heap, the stack stores local variables of primitive types, references to objects, and information about function calls. The size of the stack is fixed or limited, and data on the stack is removed when leaving the scope.

Difference	Heap	Stack
Purpose	Storage of objects, arrays	Storage of primitives, references
Allocation	Dynamic	Automatic
Management	Garbage collector / explicit	Automatic
Speed	Slower	Faster
Size	Flexible, can be large	Fixed / Limited

Example in Java:

// A reference 'myObject' is stored on the stack
MyClass myObject = new MyClass(); // The MyClass object is stored in the heap

int count = 10; // The variable 'count' (primitive) is stored on the stack

Example in Python:

# The variable 'my_list' is on the stack, the list itself is in the heap
my_list = [1, 2, 3]

# The variable 'name' is on the stack (reference), the string is in the heap
name = "Alice"

age = 30 # An integer can be stored either on the stack (small values) or in the heap (depending on Python implementation)

The specific placement can depend on the programming language, its runtime, and architecture (for example, with escape analysis, an object can be allocated on the stack even for reference types, RUST).