For many years, i have struggled with the concept of a "field", and i basically simply have no idea what a field is or how it operates, whether it is a magnetic field, gravitational field or other. when you think of a gravitational field, as per GR, you think of "curved spacetime", but what exactly is spacetime and how does it impart its curvature to objects moving within it? what exactly is curved? gravitons seem to be a particularly awkward mechanism, as, to my understanding, each particle in the universe would have to be emitting endless number of gravitons continuously. but how else does a field "communicate" with bodies? of course, a magnetic field is equally mysterious - how does a magnet move iron particles into a field pattern? are photons being emitted by the magnet which impart momentum to the iron particles to make them move into place? what are magnetic field lines? anyway, you can probably recognize my confusion, and i would appreciate any helpful comments or thoughts, or layperson level readings which might assist in my understanding of fields. thanks.