Nucleic acids, one of the most essential biological macromolecules, store and transfer genetic information of all living organisms. They comprise of four canonical units: A, T, C, and G for DNA, and A, U, C, and G for RNA. Some of these units are chemically modified to record an extra dimension of information on top of the primary sequence. The existence of these modifications has been known for decades, yet the regulation and the functions of them remained largely elusive. My doctoral work is focused on the most prevalent chemical modification on human messenger RNA, N6-methyladenosine (m6A). Understanding the regulatory mechanism and cognate functions of m6A in various biological events is crucial for the clarification of how cells encode epigenetic information into chemical modifications for global gene regulation. The characterization of m6A metabolism may also provide valuable implications for the studies of complex biological processes and human diseases.