Translation consists of three subprocesses: initiation, elongation, and termination, all involving signal motifs in mRNA and the decoding machine, including ribosomes, tRNAs, release factors, amino acids, and the energy needed to drive the translation machine. A stop codon is supposed to be decoded by release factors, but can also be misread by tRNAs, causing readthrough errors. A sense codon is intended to be decoded by tRNAs, but some of them, such as UGG, can also be misread by release factors, causing premature termination. This chapter goes far beyond the topic of translation covered in a conventional course in molecular biology and takes the reader to the research frontiers of translation. It serves two purposes: prepare the reader for understanding the inner workings of the three subprocesses in the next three chapters, especially the topic of translation optimization popularized by recent development of mRNA medicine, and to cultivate critical thinking that is needed to evaluate seemingly coherent hypotheses, including various versions of the wobble hypotheses and the hypotheses on the origin and diversification of the genetic code.