One of the most interesting challenges in modern physics is to understand, manipulate, and control materials and processes at the level of a single quantum spin. Beside fundamental interest, this research is important for applications ranging from spintronics and information processing to high-precision metrology. Nitrogen-vacancy (NV) impurity centers in diamond have recently emerged as a unique platform for investigating quantum dynamics, decoherence, and quantum control of single spins in solid-state environments. NV centers demonstrate an unusual combination of spin-dependent optical properties, individual addressability, and long spin coherence times. The NV spin state can be manipulated both optically and magnetically, and the quantum control operations can be performed with very high fidelity (>99%). Due to these uniquely favorable properties, quantum dynamics of a single NV spin can be investigated in great detail. I will discuss quantum dynamics of the NV centers, and the decohering effect of the spin bath (made of atomic nitrogen impurities) on the evolution of a NV spin. I will demonstrate how the decoherence dynamics depends on the experimental conditions. Further, I will discuss how the modern techniques of quantum control and dynamical decoupling can be employed to preserve coherence of quantum spins. Using a variety of analytical and numerical tools, we can characterize and optimize the factors which limit controllability. Finally, I will demonstrate how the theoretically optimized protocols for quantum control have been used in order to extend coherence time of individual NV spins, and how dynamical decoupling can be integrated with the gate operation in the prototype hybrid system, the electron-nuclear spin register.