Sometimes, it’s easy to get code execution in a network, but very difficult to egress out of it. When you are an external actor trying to get a foothold, it’s important that your attack package use a payload that’s likely to leave your target’s network. If you can’t get out, all of your work is wasted.
Payloads in the Metasploit Framework are staged. This means that the payload is delivered in pieces. The first piece, known as the stager, connects to you, the attacker, and downloads the second piece, known as the stage. Once the stage is downloaded, the stager executes it.