The branch of genetics concerned with the study of genomes. It has developed since the 1980s, exploiting automated techniques and computer-based systems to collect and analyse vast amounts of data on nucleotide and amino-acid sequences of various organisms, generated by projects such as the Human Genome Project. There are several distinct but overlapping areas of genomics. Structural genomics is essentially about mapping the genome and ultimately producing a complete DNA sequence for any particular organism. However, the term is often extended to include determination of three-dimensional molecular structures of nucleic acids and proteins (see proteomics). Functional genomics deals with gene expression and how gene products work. This highly complex area, which involves analysis of transcripts of sets of genes (see transcriptomics), seeks to understand how gene expression is controlled and integrated and how gene functions change under different conditions, such as disease states. Comparative genomics identifies regions of sequence similarity between genomes of different species. Knowledge of the functional significance of a particular DNA sequence in one species allows predictions about functions of closely matching sequences in other species. In addition, such comparisons permit inferences about mechanisms of gene evolution and give insights into the evolutionary relationships of different organisms. Metagenomics collectively analyses the genomes of all microorganisms in an environmental sample, such as a sample of soil or seawater (see microbiome). See also bioinformatics; metabolomics; phylogenomics.