Iron-Based Superconductors: Discovery and Progress in MaterialsHideo HosonoIntroductionSmall History on Discovery and Progress in Parent MaterialsCrystal Structure of Parent MaterialsParent Material and SuperconductivityUnique Characteristics of FeSCsSingle CrystalThin FilmSummary and Relevant New SuperconductorsSynthesis and Physical Properties of the New Potassium Iron Selenide SuperconductorR. Hu, E. D. Mun, D. H. Ryan, K. Cho, H. Kim, H. Hodovanets, W. E. Straszheim, M. A. Tanatar, R. Prozorov, W. N. Rowan-Weetaluktuk, J. M. Cadogan, M.M. Altarawneh, C. H. Mielke, V. S. Zapf, S. L. Budko, and P. C. CanfieldIntroductionExperimental MethodsCrystal Growth and StoichiometryPhysical Properties of Single Crystals of K0.80Fe1.76Se2SummaryAngle-Resolved Photoemission Spectroscopy of Iron PnictidesTakafumi Sato, Pierre Richard, Kosuke Nakayama, Takashi Takahashi, and Hong DingIntroductionExperimental ResultsConcluding Remarks and SummaryQuantum Oscillations in Iron Pnictide SuperconductorsSuchitra E. SebastianQuantum OscillationsMagnetic Field DependenceTemperature DependenceIron Pnictide SuperconductorsQuantum Oscillations in Antiferromagnetic Parent Iron PnictidesQuantum Oscillations in Overdoped Paramagnetic Iron PnictidesCuprates and Iron Pnictides: Electronic Structure ComparisonConclusionOptical Investigation on Iron-Based SuperconductorsNan-LinWang and Zhi-Guo ChenIntroductionIntroduction About Optical Properties of SolidsOptical Studies on the Parent CompoundsMulti-Components vs. Extended Drude Model Analysis of Optical ConductivityElectron Correlations in the Fe-Pnictides/ChalcogenidesAnisotropic Charge DynamicsOptical Properties of Iron-Based Superconductors Below TcAntiferromagnetic Spin Fluctuations in the Fe-Based SuperconductorsShiliang Li and Pengcheng DaiIntroductionAntiferromagnetism in Parent CompoundsMagnetic Excitations in the Superconducting StateMagnetic Excitations in the Normal StateConclusionReview of NMR Studies on Iron-Based SuperconductorsKenji Ishida and Yusuke NakaiIntroductionNMR BasicsNMR Experimental Results on Iron-Based SuperconductorsSummaryMaterial Specific Model Hamiltonians and Analysis on the Pairing MechanismKazuhiko KurokiIntroductionModel Hamiltonian ConstructionSpin Fluctuations and AntiferromagnetismSuperconductivityMaterial DependenceConcluding Remarks and PerspectivesThe Antiferromagnetic Phase of Iron-Based Superconductors: An Itinerant ApproachJohannes Knolle and Ilya EreminIntroductionA Primer: Single-Band Hubbard ModelMagnetic Order in FerropnictidesSpinWaves in Itinerant Multiorbital SystemsDiscussion and ConclusionMagnetism in Parent Compounds of Iron-Based SuperconductorsJiangping HuIntroductionExperimental Results on the Parent Compounds of Iron-Based SuperconductorsTheoretical ModelsElectronic Nematism and the Interplay Between Lattice, Spin and OrbitalDiscussion