Cryo-EM (Cryo-Electron Microscopy) allowed researchers to observe proteins in their complex conformations, structures, and modified forms. It eliminated the need for crystals and resolved concerns around purity and heterogeneity. Cryo-EM had become a popular method for scientists worldwide, contributing to research in infectious disease, neurodegenerative disease, and cancer. It played a vital role in SARS-CoV-2 research during the COVID-19 pandemic. The talk introduced Cryo-EM using the study of SARS-CoV-2 structures as an example.