Transcriptomics, the study of the complete set of RNA transcripts produced by the genome, has become a central tool in the post-genomic era for understanding gene expression and regulation. It provides critical insights into cellular functions, developmental processes and responses to environmental or physiological stimuli. Techniques such as microarrays and RNA-sequencing (RNA-Seq) have revolutionized transcriptome profiling by enabling comprehensive quantification of both coding and non-coding RNAs. These methods not only identify novel transcripts and splicing variants but also uncover expression patterns underlying disease mechanisms, stress tolerance and developmental regulation. Transcriptome data further support integrative analyses in systems biology, linking gene activity to protein networks and metabolic pathways. Thus, transcriptome analysis serves as a foundational approach for discovering biomarkers, functional genes and therapeutic targets, significantly advancing personalized medicine and crop improvement.