The spin-transfer torque (STT) phenomenon has recently been utilized for magnetic nano spin-transfer torque oscillators (STO) in patterned or nano-contact spin valves and magnetic tunnel junctions (MTJ). For applications, synchronization of multiple oscillators to achieve a higher microwave power and lower bandwidth is required. In order to realize such synchronization, a mutual feedback system among the nano STOs is required. Spin wave mediated interaction of two nano-contact STOs was the first demonstration of STOs synchronization. Despite many efforts, maximum four STOs have been experimentally synchronized so far. A new type of oscillator based on the spin-Hall effect (SHE) has been introduced, in which the oscillation mode is a self-localized spin wave bullet, and its injection locking has been demonstrated as well. The spin Hall oscillators (SHO) can be also realized in nano-magnetic elements.