From the [tutorial](https://docs.sel4.systems/Tutorials/capabilities):
There are three kinds of capabilities in seL4:
- capabilities that control access to kernel objects such as thread control blocks,
- capabilities that control access to abstract resources such as `IRQControl`, and
- untyped capabilities, that are responsible for memory ranges and allocation from those (see also the [Untyped](https://docs.sel4.systems/Tutorials/untyped.html) tutorial).