Exploits are entry points which allow further homebrew to be run. In the main guide, you will use exploits such as the browser exploit (http://wiiuexploit.xyz) and PayloadLoader (Health & Safety exploit). All current exploits load `SD:/wiiu/payload.elf` which takes over further loading of homebrew.
Payloads, which are normally found with the filename `payload.elf`, exist to make it easier to have different exploits load the same next stage, which allows easier updateability. It doesn't matter what exploit loads the payload, the result is always the same. Multiple payloads can be switched between using the PayloadLoaderPayload. The payload used in the main guide is CustomRPXLoader which loads `SD:/wiiu/payload.rpx` and the `payload.rpx` used in the guide is EnvironmentLoader, which allows you to load different environments.
An environment is a collection of "setup modules", which will be run in a certain order when launching the environment. One such environment is Tiramisu. Setup modules are small pieces of homebrew/code that are executed once to set up an environment.
### Can I install games from my USB instead of SD?