This tutorial briefly introduces the important principles of quantum error correction and quantum error-correcting codes. We look at classical error correction, and the important limitations in working with quantum information. The basic structure of a quantum code is laid out, and how errors are detected and corrected. We introduce stabilizer codes and their connection to classical linear codes, and show how quantum codes can be constructed from classical codes. The problem of encoding and decoding is briefly discussed. Finally we touch on degeneracy and passive error correction in quantum codes.