eLS, formerly known as The Encyclopedia of Life Sciences, is the largest single reference work ever published in the biological sciences. Its core subjects include Biochemistry, Cell Biology, Developmental Biology, Evolution, Genetics & Molecular Biology, Immunology, Microbiology & Virology, Neuroscience, Plant Science, and Structural Biology. Its 3000 articles are peer-reviewed and regularly updated; some are aimed at the general reader and some at researchers in the field and the level is clearly designated. The encyclopedia may be browsed by article title, subject or contributing author, or searched by keywords.