RNA sequencing is a laboratory technique used to analyze the complete set of RNA molecules in a cell or tissue at a specific time. This process involves converting RNA into complementary DNA (cDNA) and then sequencing it to determine the quantity and sequences of the RNA present. This information helps researchers understand gene expression and regulation. By comparing RNA sequencing data from different samples, scientists can identify which genes are active under various conditions, such as in healthy versus diseased tissues. This technique is crucial for advancing our knowledge in fields like genomics, transcriptomics, and personalized medicine.