The paper provides an experimental review of the pseudogap phenomenon in high-temperature superconductors, focusing on cuprate materials. Various experimental techniques, including angle-resolved photoemission spectroscopy (ARPES), tunneling spectroscopy, nuclear magnetic resonance (NMR), and transport properties, are discussed to understand the nature and characteristics of the pseudogap. The pseudogap is observed across different cuprate families and is characterized by a partial gap in the electronic density of states, which persists into the normal state. The d-wave symmetry of the superconducting gap is consistent with the pseudogap, and the pseudogap is found to emerge from the normal state. The review highlights the lack of consensus on the origin of the pseudogap and the mechanisms underlying high-temperature superconductivity. Key findings include the temperature and doping dependence of the pseudogap, its relationship with the superconducting gap, and the implications for the Fermi surface and electronic structure.The paper provides an experimental review of the pseudogap phenomenon in high-temperature superconductors, focusing on cuprate materials. Various experimental techniques, including angle-resolved photoemission spectroscopy (ARPES), tunneling spectroscopy, nuclear magnetic resonance (NMR), and transport properties, are discussed to understand the nature and characteristics of the pseudogap. The pseudogap is observed across different cuprate families and is characterized by a partial gap in the electronic density of states, which persists into the normal state. The d-wave symmetry of the superconducting gap is consistent with the pseudogap, and the pseudogap is found to emerge from the normal state. The review highlights the lack of consensus on the origin of the pseudogap and the mechanisms underlying high-temperature superconductivity. Key findings include the temperature and doping dependence of the pseudogap, its relationship with the superconducting gap, and the implications for the Fermi surface and electronic structure.