Abstract: Spintronics is a field of research and technology that exploits the electron’s spin—a quantum property responsible for magnetism—along with its charge, as used in conventional electronics. In spintronic devices, information can be stored, processed, and transmitted through the control of spin orientation in addition to charge flow. While most established spintronic concepts rely on ferromagnets—materials with a large net magnetization, recent advances have brought antiferromagnets into focus. Antiferromagnets are magnetically ordered materials with a fully compensated net magnetization, meaning their opposing spin sublattices cancel each other. Owing to their robustness against external magnetic fields, absence of stray fields, and ultrafast spin dynamics, antiferromagnetic spintronic devices promise higher integration density and lower energy consumption than their ferromagnetic counterparts. This talk will review the key physical principles and phenomena underpinning functional spintronic devices, with an emphasis on the fundamental mechanisms governing their operation. Using the magnetic tunnel junction (MTJ) as a representative example—an essential component of modern magnetic random-access memory (MRAM), the discussion will highlight the core effects that make such devices functional. New functionalities arising from the unique physics of antiferromagnets will be then introduced and discussed. Their terahertz spin dynamics, spin torque–driven Néel vector control, and symmetry-dependent spin transport phenomena reveal a rich landscape of emergent phenomena, pointing to fundamentally new directions in spintronic research.