While "genomics" is becoming a household term, knowing the genome of an organism alone provides relatively little information. Between the genome and the final organism is the "transcriptome" that tells us which genes are expressed and translated into proteins in a certain cell or tissue of an organism at a given time and specific situation. The transcriptome tells you what genes are being "transcribed" at any given moment, providing the wealth of data and specificity of proteomics with the relative ease of study of genetics. Transcriptomics technology thus has myriad uses, and the goal of this book is to showcase the extraordinary diversity of ways transcriptomics can be utilised in entomological research, from basic to applied, from ecology to physiology to agricultural.