Both the development and maintenance of nuclear technologies rely on the availability of nuclear data to provide accurate numerical representations of the underlying physical processes. Essential data include energy-dependent reaction probabilities (cross sections), the energy and angular distributions of reaction products for many combinations of target and projectile, and their radioactive decay data. The IAEA Nuclear Data Section is responsible for development and dissemination of nuclear data for applications. I will introduce its organization structure, major databases, and international network of data centers and evaluators. Finally details will be presented for the experimental nuclear data library (EXFOR) where various useful neutron-, proton- and photo-induced reaction data measured at POSTECH (Pohang Univ. of Science and Technology, Pohang) and KIRAMS (Korean Institute of Radiological & Medical Sciences, Seoul) coordinated by KNU have been compiled by Korean data compilers last years.