  This short article highlights the unsolved problems of magnetic reconnection
in collisionless plasma. The advanced in-situ plasma measurements and
simulations enabled scientists to gain a novel understanding of magnetic
reconnection. Still, outstanding questions remain on the complex dynamics and
structures in the diffusion region, on the cross-scale and regional couplings,
on the onset of magnetic reconnection, and on the details of energetics. Future
directions of the magnetic reconnection research in terms of new observations,
new simulations and interdisciplinary approaches are discussed.
