Molecular genetics underlies the majority of modern biological research. It is concerned with the molecular mechanisms by which genes are expressed and regulated and the ways in which they control the properties of cells and organisms. Molecular genetics has been revolutionised in recent years by the availability of large DNA sequence datasets, including full genome sequences for many species. This has also facilitated the study of many human traits, including diseases that have a major genetic component but whose inheritance involves more than a single gene. Genetics impacts on almost every aspect of our lives - from human genetics and health, to infectious disease, what we eat and drink and how we live.