For a quantum computer to work, it takes extreme precision to isolate and control qubits. In particular, qubits are very short-lived due to the interactions with the environment. Quantum logic gates can have small drifts when pulses are out-of-focus or out-of-tune. Classical controls and calibrations may have a hard time keeping up in scale, speed, and power. If there were no strategies to overcome the aforementioned examples of noises, they would accumulate and eventually lead to critical failure in computation. Physical noises in current devices put stringent limitations on their computing capabilities. Indeed, this chapter aims to address the central issue: how do we protect information from the adverse impacts of noise? We highlight two classes of strategies that have been developed for information protection and error reduction in quantum systems, namely noise mitigation and error correction. In both cases, we demonstrate a few promising examples that effectively lower the error rates, and then stress the drawbacks and challenges that still remain.