Marshalling is a process of transforming an "object" in memory into a format that can be communicated over a network. The object would be "unmarshalled" at the other end to replicate it there. Sorta like serialization. This is often used for Remote Procedure Calls (RPC). Garbage Collector is a mechanism in managed programming languages that scans for items using memory and automatically frees up memory of items that are determined to never be used for the remainder of program execution.