The transcriptome refers to the complete set of RNA molecules present in a single cell or a population of cells at a given time. It can include all types of RNA or be limited to messenger RNA (mRNA), depending on the experiment's focus. Unlike the exome, which represents only the protein-coding regions of DNA, the transcriptome captures the actively expressed genes by identifying RNA molecules and their relative abundance. This provides crucial insights into gene expression patterns, cellular functions, and responses to environmental changes.