Is it something you consciously do or not? I consciously rock when alone. I am not aware of rocking and tapping my feet when my stepdaughter is with me. However at my third assessment she said I rock and tap my feet. I'm not aware of anything else I do that could be called stimming.
Both, I think - a bit like breathing. Often it just happens, often you're aware of it, sometimes it's semi-deliberate.
(I know that breathing happens more reliably than "often" but you get the idea :-) )
I have verbal/vocal and motor tics and stims.
The tics start as involuntary, but often then turn into voluntary stims. Some of my stims start without me noticing as well. Verbal ones include the word "chicken" (on seeing/hearing the word, or the animal); the word "wales" in a dreadful fake Welsh accent (on hearing anybody welsh, especially that weatherman on the bbc); and a new vocal one is going "woof" at dogs if I drive by.
Motor ones are rocking, facial grimacing, walking in a wavy path rather than a straight line, sitting cross legged (this is a deliberate calming mechanism I guess rather than a true stim).
I am still only starting to understand my stims, but I think i like them!!