The garbage collector in .Net takes care of the bulk of the memory management responsibility, freeing up the developer to focus on core issues. The garbage collector is optimized to perform the memory free-up at the best time based upon the allocations being made. Up until now, two techniques have been used on the Windows platform for deallocating memory that processes have dynamically requested from the system:

• Make the application code do it all manually.
• Make objects maintain reference counts. 

Having the application code responsible for deallocating memory is the technique used by lower-level, high-performance languages such as C++. It is efficient, and it has the advantage that resources are never occupied for longer than necessary. The big disadvantage, however, is the frequency of errors. A code that requests memory also should explicitly inform the system when it no longer requires that memory. However, it is easy to overlook this, resulting in memory leaks. 

The .NET runtime relies on the garbage collector instead. This is a program whose purpose is to clean up memory. The idea is that all dynamically requested memory is allocated on the heap, which is true for all languages, although in the case of .NET, the CLR maintains its own managed heap for .NET applications to use. When .NET detects that the managed heap for a given process is becoming full and therefore needs tidying up, it calls the garbage collector. 

 The garbage collector runs through variables currently in scope in code, examining references to objects stored on the heap to identify which ones are accessible from the code—that is to say which objects have references that refer to them. Any objects that are not referred to are deemed to be no longer accessible from your code and can therefore be removed. 

One important aspect of garbage collection is that we cannot guarantee when the garbage collector will be called; it will be called when the CLR decides that it is needed, unless we explicitly call the collector, though it is also possible to override this process and call up the garbage collector in our code. 

To call garbage collector in our code we can force garbage collection by invoking the GC. Collect method from the program. The System.GC class provides methods that control the system garbage collector.