Where is the (detailed) documentation for all the different types of helpers

I am trying to find out which type of helper can do what kind of functionality.
But besides the very limited information when you add one in the userinteface, I cannot find any documentation.
(There are a lot more types than last time I added a simple number helper)

And please make up your mind… is “Generic Thermostat” a helper or an integration?

And now I cannot delete a statistics helper…

HEEEEELLLLP

ok… found it… but cant google it or get it referred on the main page.
The link “Tools and Helpers” points to

Which tells NOTHING about HELPERS (or tools for that matter)

I was looking for

And you found it.