RNA-sequencing (RNA-seq) is a powerful method for studying the transcriptome—the entire spectrum of coding and noncoding RNA transcripts present in a cell or tissue. The transcriptome can provide valuable insights into cellular behavior at a particular moment, whether at rest or when responding to changes in the environment, therapeutic treatments, or developmental progression. RNA-seq also enables the identification of variant splicing events, novel transcripts, mutations, gene fusions, isoforms, and single nucleotide variants (SNVs).