Apollo is a genome annotation viewer and editor. It was developed as a collaboration between the Berkeley Drosophila Genome Project (part of the FlyBase consortium) and The Sanger Institute in Cambridge, UK. Apollo allows researchers to explore genomic annotations at many levels of detail, and to perform expert annotation curation, all in a graphical environment. It was used by the FlyBase biologists to construct the Release 3 annotations on the finished Drosophila melanogaster genome, and is also a primary vehicle for sharing these annotations with the community. The Generic Model Organism Database (GMOD) project, which aims to provide a complete ready-to-use toolkit for analyzing whole genomes, has adopted Apollo as its annotation workbench.