Or at least, their notion doesn’t really help us understand physics better. This physicist prefers to think of them as a (useless) interpretation of ripples of a field. The electromagnetic field may have a ‘natural’ ripple, called a photon. Or it may have a ‘forced’ ripple, such as between passing electrons, called a virtual photon or just a ripple in the electromagnetic field. I never really understood what to picture when my professors spoke of this exchanged, it somehow being mediated by virtual photons wasn’t really clear. How many, sprining continuously back and forth? The notion of just calling it a ripple is more satisfying and clear, I think. Thanks, prof. Matt Strassler!