Drawing a line of vertices between two points

I’m trying to follow an off-site tutorial and the guy selects two points and creates a line of vertices between them. Kind of like a loop that doesn’t go across any faces. I cannot find the hot key to do this.

Does anyone know how to do this?

you mean fill? (F)

No, I see ctrl LMB creates a vertice. I’m an idiot lol. Thanks though.