  Antiferromagnetic (AFM) spintronics has emerged as a subfield of spintronics,
where an AFM N\'eel vector is used as a state variable. Efficient electric
control and detection of the N\'eel vector are critical for spintronic
applications. This review article features fundamental properties of AFM tunnel
junctions (AFMTJs) as spintronic devices where such electric control and
detection can be realized. We emphasize critical requirements for observing a
large tunneling magnetoresistance (TMR) effect in AFMTJs with collinear and
noncollinear AFM electrodes, such as a momentum-dependent spin polarization and
N\'eel spin currents. We further discuss spin torques in AFMTJs that are
capable of N\'eel vector switching. Overall, AFMTJs have potential to become a
new standard for spintronics providing larger magnetoresistive effects, few
orders of magnitude faster switching speed, and much higher packing density
than conventional magnetic tunnel junctions (MTJs).
