RNA sequencing, also known as RNA-Seq, is a technology that allows researchers to analyze gene expression in a cell or tissue by measuring the levels of RNA molecules present. This technique provides valuable information on which genes are active in a particular biological sample, and can be used to identify differentially expressed genes, splice variants, and non-coding RNAs. RNA sequencing has become a powerful tool in biological research, allowing for a more comprehensive understanding of gene regulation and expression patterns in various biological processes and diseases. It has applications in fields such as genomics, transcriptomics, and personalized medicine.