So in simple diagrams like this for problem solving I've over time came to recognize and understand what the different symbols and elements mean, such as pins/rollers, force and force distributions, etc. This is all relatively fundamental and important to convey the phenomena of occurrences that happen in crafting diagrams such as work problems for school. That said I never learned exactly what this kid of technical art is called nor was I ever given what I consider a sufficient background in it. Even simple concepts like the diagonal lines used to denote the rigid immobile floors/walls of the environment I have no clue what to refer to as simply.
Is this sort of pictorial representation used so simply in the professional/scientific world and how developed is it? I want to learn formal terms and expand my knowledge of more common terms and symbols, such as the roller contact points characterized by circles in pic related.