What are the magnetic field lines basically depicting in terms of moving charges or charge carrier particles or currents.
What do those circular loops around a straight current carrying wire actually tell us? Do they provide information regarding direction and flow of currents?
Do magnetic lines of force depict path of moving charges or their velocity field or axes of rotation?
NB: I already know that magnetic lines represent the directions in which a compass needle or magnetic monopole (if one existed) and also that it signifies the direction of vector B. This in textbooks all over the place.(this is not the information I am seeking).
Now to go one step further may I ask what does this "direction of the magnetic field ⃗B" physically signify/indicate.