Book excerpt: Helicases are ubiquitous enzymes found throughout evolution. Research in the helicase field has been going on for a long time now but in recent past with the completion of so many genomes, these enzymes have been discovered in a number of organisms. But the available literature is scattered. The huge number of identified DNA and RNA helicases, along with the structural and functional differences among them, make difficult for the interested scholar to grasp a comprehensive view of the field. Helicases from all Domains of Life is the first book to compile information about helicases from many different organisms in one place. Knowledge of the functions and features of helicases across the different kingdoms of life are a valuable source of novel ideas and information The book begins with a chapter on the evolutionary history of helicases followed by three "overview" chapters: one for bacteria/archaea (which are not mentioned), one for plants/algae and one for human helicases The overview chapters are followed by specific chapters on selected helicases of great importance from a biological/applicative point of view