Inject javascript into any running process (or python, or golang, or any of a bunch of other langauge bindings).

Can be used to hook into processes, run functions, send and receive messages, and a bunch more.
Essentially process injection on steroids - super cool.

It seems to even be able to inject itself to processes on other devices running connected to the machine? Not entirely sure how to implement but take a look at frida-ps ios example.