Thanks to the efforts of the Human Genome Project, the draft human genome is out there for every molecular biologist to use, but we're not all gene jockeys. The NCBI's draft human genome sequence: an introduction gets inside the head of a molecular biologist who has never had to navigate his/her own DNA before, and poses the questions that s/he might ask. For one question — 'is there only one copy of ALD (the adrenoleukodystrophy gene) in the genome?' — a detailed tour of the draft genome is provided, with a subway map that explains how the draft human genome data intersect with the NCBI's other resources. Each question takes you to the type of search that you need to perform, complete with a 'help' window explaining what it's just done and where you can go from there. So, whether you're interested in intron–exon structure, single nucleotide polymorphisms, homologous sequences or protein domains and their structures, the tour tells you which train to catch and where you need to change lines.

One stop along this tour has been significantly refurbished. By now, all readers of Nature Reviews journals will be familiar with the NCBI's LocusLink database as all our articles carry extensive links to it. Each LocusLink entry now provides links to the Gene Ontology database (providing information on molecular function, biological process and cellular component), Proteome's databases of protein function (you have to register, but access is free to not-for-profit organizations), the Mouse Genome Database and Flybase. The wealth of functional data provided by these links make this the Grand Central Station of the NCBI's tour.