Elementary particles have no volume! (think about that one, it's kinda mindblowing) They can only have "effective size" that arises due to say, electromagnetis

Elementary particles have no volume! (think about that one, it's kinda mindblowing) They can only have "effective size" that arises due to say, electromagnetism. The electron has an effective radius that is measured by bouncing other charged "test" particles off of it. You don't get an answer of zero only because your test particles are attracted or repelled by the electron. Mass should be thought of as something intrinsic to a particle, just like charge or spin. There's really no good way to visualize it - it's just something different particles have in different amounts.