How do I get a list of commands starting with a certain key (combo) in Emacs?

Question

I can use C-h c (describe-key-briefly) and type a key combination and it will return me the function bound to it. But I'd also like to type only a prefix of a key combination and have it list and describe all functions bound to key sequences starting with it, like "all bound keys starting with C-x".

Answer 1

Do the key combo then C-h. For your example of C-x, do C-x C-h. This also works with sub-maps, e.g. C-x r C-h to see everything under C-x r