Hui Chieh Teoh2025-01-092025-01-0920209781799823810978179982383410.4018/978-1-7998-2381-0.ch015https://dspace-cris.utar.edu.my/handle/123456789/11204The cosmic microwave background (CMB) holds many secrets of the origin and the evolution of our universe. This ancient radiation was created shortly after the Big Bang, when the expanding universe cooled and became transparent, sending an afterglow of light in all directions. It is a pattern frozen in place that dates back to 375,000 years after the birth of the universe. Numerous experiments and space missions have made increasingly higher resolution maps of the CMB radiation, with the aims to learn more about the conditions of our early universe and the origin of stars, galaxies, and the large-scale cosmic structures that populate our universe today.book-chapter