The Species 2000 & ITIS Catalogue of Life will become the comprehensive catalogue of all known species of organisms on Earth. Started in 2000, it is hoped to be complete by the year 2011. As things stand, the catalogue has just reached 1,008,965 species: probably just more than half of the world’s known species. (The final total is expected to be around 1.75 million.)

The catalogue is compiled with sectors provided by 47 taxonomic databases, many containing data and opinions from extensive networks of specialists, so that the complete work contains contributions from more than 3,000 specialists from throughout the taxonomic profession. These databases are peer-reviewed by teams from the Species 2000 and ITIS programme, who also select appropriate sectors and integrate them into a single coherent catalogue with a single hierarchical classification.

It is planned to introduce alternative taxonomic treatments and alternative classifications, but an important feature is that for those users who wish to use it, a single preferred catalogue, based on peer reviews, will continue to be provided.