The International Linear Collider (ILC) Technical Design Report 2013, Volume 4: Detectors, outlines the detailed baseline design of two detector concepts, SiD and ILD, for the ILC. The report discusses the physics and detector challenges of the ILC, including the need for high precision measurements of the Higgs boson and other particles. The ILC is designed to operate at energies up to 1 TeV, with beam polarisation that enhances the sensitivity of experiments. The report details the detector requirements, including the need for high granularity calorimeters, precise tracking systems, and efficient muon systems. The SiD detector is a compact, cost-constrained detector using silicon tracking in a 5 Tesla magnetic field, while the ILD is a large detector optimised for resolution and track separation. Both detectors use low-mass, high-resolution vertex detectors and operate with a triggerless readout. The report also discusses the development of common software tools, simulation techniques, and engineering solutions for the detectors. The ILC's detector design is closely integrated with the machine's beam delivery system, and the detectors are designed to operate in a push-pull configuration to allow for maintenance and upgrades. The report concludes that the ILC detectors are mature concepts, backed by detailed R&D studies, and that further engineering work is needed to advance the technology.The International Linear Collider (ILC) Technical Design Report 2013, Volume 4: Detectors, outlines the detailed baseline design of two detector concepts, SiD and ILD, for the ILC. The report discusses the physics and detector challenges of the ILC, including the need for high precision measurements of the Higgs boson and other particles. The ILC is designed to operate at energies up to 1 TeV, with beam polarisation that enhances the sensitivity of experiments. The report details the detector requirements, including the need for high granularity calorimeters, precise tracking systems, and efficient muon systems. The SiD detector is a compact, cost-constrained detector using silicon tracking in a 5 Tesla magnetic field, while the ILD is a large detector optimised for resolution and track separation. Both detectors use low-mass, high-resolution vertex detectors and operate with a triggerless readout. The report also discusses the development of common software tools, simulation techniques, and engineering solutions for the detectors. The ILC's detector design is closely integrated with the machine's beam delivery system, and the detectors are designed to operate in a push-pull configuration to allow for maintenance and upgrades. The report concludes that the ILC detectors are mature concepts, backed by detailed R&D studies, and that further engineering work is needed to advance the technology.