Coherent control and readout of single spins in solids is attracting considerable attention, owing to potential application of atomic- scale technologies in novel information processing protocols and sensing at the nanoscale [38]. Spins are particularly interesting candidates for achieving such control, owing to the long coherence time. This isolation from the environment makes the readout of individual spins quite challenging. It was shown that the magnetic moment associated with single quantum systems can be detected in transport measurements with single quantum dots [25] and defects in silicon [81]. Magnetic resonance force microscopy was also able to reach the ultimate sensitivity regime [65]. Recently developed optical readout techniques explore new avenue in single-spin de- tection by combining high-sensitivity optical microscopy techniques and conventional magnetic resonance control methods. Following detection of single molecular spin [80], quantum states associated with single defects in diamond were explored [29]. Experiments with single defects in diamond are particularly interesting owing to the long coherence time associated with spins of color centers. This chapter shows the basics of single-spin detection and highlights the importance of coherent control of spins in solids for novel quantum technologies.