Serial analysis of gene expression (SAGE) is a powerful technique that allows for the quantitative analysis of gene expression in a high-throughput, genome-wide manner. However, there are multiple synonyms for SAGE, including tag-based sequencing, serial gene expression analysis, and transcript profiling. These terms all refer to the same concept of quantifying mRNA expression levels for thousands of genes simultaneously. Other variations on these terms include tag sequencing and serial expression analysis. This type of analysis has revolutionized the study of gene expression and has provided insights into the complex networks of genes that orchestrate the dynamic processes of life.