A transcriptome is the full range of messenger RNA, or mRNA, molecules expressed by an organism. In contrast with the genome, which is characterized by its stability, the transcriptome actively changes. In fact, an organism’s transcriptome varies depending on many factors, including stage of development and environmental conditions (Scitable by Nature Education).
Two main techniques are used to study the transcriptome, namely microarray and RNA-seq. RNA-seq is based on Next Generation Sequencing (NGS) platforms.