Stack vs Heap in .NET: How Memory Allocation Actually Works in C#

In .NET, memory is managed across two key areas: the stack, which handles method calls and local execution data in a fast, last-in-first-out manner, and the managed heap, where objects are allocated and later cleaned up by the Garbage Collector. A common misconception is that value types always live on the stack and reference types always on the heap, but actual placement depends on storage context — for instance, a value-type field inside a class resides on the heap as part of that object. Strings, though reference types, are immutable, meaning any apparent modification creates a new string object rather than altering the original. The .NET Garbage Collector reclaims heap memory when objects become unreachable, though collection timing is not immediate and is determined by the runtime. Understanding these allocation patterns matters for performance, as creating large numbers of short-lived objects can increase GC activity, making it important to avoid unnecessary allocations in performance-sensitive code.