The Encyclopedia of Life Support Systems (EOLSS) is an integrated compendium of twenty one encyclopedias. The first Earth Summit of 1992, held in Rio de Janeiro, issued a document that is now famous as Agenda 21. This document refers to the Earth's life support systems, considering the whole of our planet as a grand intensive care unit that supports all forms of life (both natural and human-engineered systems). The EOLSS is based on this concept and the above definition of 'life support systems'. Unlike most encyclopedias, the contents of which are alphabetically arranged, EOLSS has a thematic organization (Theme Level, Topic Level and Article Level). It can be regarded as an 'encyclopedia of encyclopedias', presenting a wide range of major foundation subjects in a process of gradual devel