The transcript is essential for the genome to convey its information to the world. The RNAs produced by transcription can have an enormous array of potential functions. Some RNAs encode messages that will be translated into proteins. Other RNAs become processed into small fragments that are essential for cellular regulation. Yet others may possess catalytic activity and form core components of cellular machines such as the ribosome and spliceosome. Understanding RNA biochemistry, the many roles of RNA in the cell, and how RNA transcripts can be modified and subject to regulation is essential for understanding life itself.